A history of gaining experience in D&D

Brown Book D&D (1974)

Originally, D&D awarded XP for treasure gained and monsters defeated. The actual XP rewards were not included in the books, though an example of calculating XP for an encounter was:

Experience Points: Experience points are awarded to players by the referee with appropriate bonuses or penalties for prime requisite scores. As characters meet monsters in mortal combat and defeat them, and when they obtain various forms of treasure (money, gems, jewelry, magical items, etc.), they gain "experience". This adds to their experience point total, gradually moving them upwards through the levels. Gains in experience points will be relative; thus an 8th level Magic-User operating on the 5th dungeon level would be awarded 5/8 experience.

Though the actual rewards are never listed definitively (an ommission that would be repeated by the "Blue Book" Basic of 1977), we can infer some practices:

1. XP for monsters was based on monster level; many groups assumed 100xp per HD (see Greyhawk, below).
2. XP for treasure was 1xp per gp.
3. XP was scaled for each character, based on relative level to the monster, who typically matched the dungeon level.
4. XP was scaled for each character based on their Prime Requisite scores; higher scores gave an XP bonus and was the primary means by which exceptional scores benefitted characters.

The first rule was contentious enough to require errata, but even groups playing under these rules would see a gradual shift in the primary source of XP as characters gained levels.

Low-level characters facing a typical group of low-level monsters, say a lair of kobolds, would earn XP primarily from slaying the monsters themselves, and a comparatively small amount of XP from the treasure obtained. A small (!) lair of 40 kobolds would yield around 200gp in treasure (140 from the 1d6-per-enemy, and around 60, with wide variance, from the level 1 lair treasure expected to appear in any room containing a monster). That's 4000xp from monsters and 200xp from treasure.

By the time the party was fighting 5HD enemies, though, this was a different story. A half-dozen Mummies or Cockatrices (both treasure type D) would yield 3000xp from the monsters, but another 3000xp from treasure (~700gp from the "lair" treasure, and ~2300gp from treasure type D). From here, XP from treasure outpaced XP from monsters, with dragons earning tens of thousands of GP while only being worth perhaps two thousand XP for simple slaying.

Supplement 1: Greyhawk (1976)

The incompleteness of the original D&D printing led to Gygax making drastic changes in the form of a supplemental pamphlet. In this, he and Kuntz address the XP system:

Guidelines for A warding Experience Points for Monster Slaying: (Addition)

The awarding of experience points is often a matter of discussion, for the referee must make subjective judgments. Rather than the (ridiculous) 100 points per level for slain monsters, use the table below, dividing experience equally among all characters in the party involved.

This change would be canonized in the rest of the Basic lineage, reprinted verbatim in the Blue book (1977) as well as influencing the AD&D rules. The table image above is from Expert, but the numbers remained largely unchanged throughout the Basic lineage.

It's clear that Gygax's intent would continue to emphasize XP from treasure over XP from killing monsters, only now this was true even at very low levels - those 40 kobolds are now worth 300xp from slaying, but the same 200xp from average treasure found; the cockatrices worth 1800xp from slaying but 3000xp from average treasure.

Basic (1977 - 1983+)

Moldvay Basic (the first "Red Book", TSR2014) lists treasure as the first source of XP, and then reprints the XP-per-HD table, expanding the rules and procedures for awarding XP:

• XP rewards for encounters include "monsters killed or overcome by magic, fighting, or wits."
• XP for treasure was allocated by the DM, even if the party decides to split treasure in a different way.
• DMs were encouraged to increase rewards for exceptionally tough encounters.
• DMs were permitted to reward partial XP for encounters the party doesn't win, but learns from anyway.
• DMs awarded XP to surviving members of a party, at the end of an adventure. This nuance technically means survivors benefit from the deaths of other adventurers, though in practice most groups would allow replacement PCs who would recieve XP earned by the characters they were replacing.
• XP was capped at one level per "adventure" - if you recieved enough to gain a second level, you earned just enough to be 1xp shy of that level. When followed, this rule lead to PCs seeking out short adventures to earn a few xp before diving back in to a longer adventure...

Mentzer Basic (the boxed "Red Book", TSR1011B) changed the rules in some small but significant ways:

• XP for monsters was only given for slain or "conquered" monsters, but not those that flee.
• XP for treasure now matched the split the party decided on, not the DM, so parties that gave more gold to PCs that didn't recieve magic items (which weren't worth XP) got more XP instead.

Both Basic books continued the Prime Requisite bonus XP, but reduced it to 5-10% from the original 10-20%. Both books also codified rules that NPCs recieved half a share of both the treasure and XP for monsters.

Companion (TSR1013, 1984), added some adventure design guidelines that revealed some further design intent. First, On most adventures, XP gained from defeating monsters should be 1/5 of the total XP. Second, it made the first mention of "bonus XP", suggesting ad-hoc rewards for "completion of a goal (rescue, retrieving an item, etc.), special individual actions (heroic performance, exceptional or frequent use of special abilities), alignment play, or other aspects of the overall adventure." This wasn't a new idea - such bonuses had already been mentioned infrequently in published modules. For example:

• B2, Keep on the Borderlands, granted an ad-hoc reward for destroying evil writings (or keeping them if the party is evil).
• B5, Horror on the Hill, granted an ad-hoc reward for destroying supplies of a mustering Hobgoblin assault force.
• B9, Castle Caldwell and Beyond, has ad-hoc rewards for cleverness in dealing with a trap,
• X1, Isle of Dread, offered the unique option to grant XP to players if they set up a trade route to the island.
• An adventure in the Companion book itself offers a hefty XP reward to PCs that win a jousting tournament.

Gazetteer made significant contributions to Basic throughout the 80s. A few options for the XP system were added. For example:

• GAZ2, The Emirates of Ylaruam (TSR9194, 1987) make heavy use of small rewards to reward roleplaying the distinct culture of the setting; PCs earn XP for behaving honorably, suggesting 1/100th of the XP needed to reach the next level, or a 5% bonus at the end of an adventure. Elsewhere, more design intent is revealed, suggesting a PC's XP should come 1/5 from defeating monsters, 1/5 to 2/5 from treasure, and the remaining 1/5 to 2/5 from goals, honor challenges and good roleplaying.
• GAZ3, Principalities of Glantri (TSR9208, 1987) introduces many new options for magic users, along with a new ways for them to earn XP: creating magic items, researching new spells, acquiring rare knowledge (a reason to adventure), etc. Along with these new options are suggestions that magic users earn less for treasure and monster-slaying, lending motivations other than traditional adventuring.

Rules Cyclopedia (TSR1071, 1991) collected many of these and standardized the ad-hoc awards, establishing five sources of XP:

• Roleplaying Awards were 1/20th of the base XP needed to advance to the next level. (E.g. a fighter reached level 4 at 6,000 xp, and will reach level 5 at 12,000 xp; a 1/20th award is therefore 300xp). These could be heroism, good alignment play, etc, but the DM was advised to limit this to once per session.
• Goal XP was equal to the XP value for all of the monsters defeated in achieving that goal. Confusingly, this wasn't divided among the party; the party would earn a share of monster XP for fighting monsters, but then the entire XP was awarded to each PC again if the goal of the adventure was achieved.
• Monster XP - as in prior books, XP for fighting monsters, divided among PCs. Monsters fought but not defeated were worth 1/4th their value.
• Treasure XP - 1 per GP, as in prior books. This also included payments or rewards PCs earned for finishing an adventure.
• Exceptional Actions - another 1/20th of next level award. A bit nebulous, but the examples given include saving other party members from harm, or pulling off exceptionally difficult or unusual uses of skills.

By this point it was clear that XP from sources other than killing monsters were the primary means of attaining higher levels, especially after the first few levels.

AD&D First Edition (1979)

1e brought back a lot of Gygax's early ideas about adjusting monster XP by PC level:

Dividing the total adjusted hit dice equivalent of the monsters slain by the total of all levels of experience of all characters who had a part (even if only 1 missile, blow, spell, etc.) in the slaying yields a fraction which is the measure of challenge. If the numerator is greater than the denominator, then full experience should be awarded. If the denominator is greater, use the fraction to adjust the amount of experience by simple multiplication.

XP for treasure was also retained, though the un-named challenge ratio mentioned also applied here:

If the relative value of the monster(s) or guardian device fought equals or exceeds that of the party which took the treasure, experience is awarded on a 1 for 1 basis. If the guardian(s) was relatively weaker, award experience on a 5 g.p. to 4 x.P., 3 to 2, 2 to 1, 3 to 1, or even 4 or more to 1 basis according to the relative strengths.

Magic items were also worth XP, beginning a tradition of listing both XP value and GP value for magic items that would last into second edition.

An amusing side-note was added, suggesting Gygax was already facing players annoyed by XP-for-treasure:

Note: Players who balk at equating gold pieces to experience points should be gently but firmly reminded that in a game certain compromises must be made. While it is more "realistic" for clerics to study holy writings, pray, chant, practice self-discipline, etc. to gain experience, it would not make a playable game roll along. Similarly, fighters should be exercising, riding, smiting pelts, tilting at the lists, and engaging in weapons practice of various sorts to gain real expertise (experience); magic-users should be deciphering old scrolls, searching ancient tomes, experimenting alchemically, and so forth; while thieves should spend their off-hours honing their skills, "casing" various buildings, watching potential victims, and carefully planning their next "job". All very realistic but conducive to non-game boredom!

It would seem that the Gazetteer authors agreed with the Gygax's premise, but not the conclusion...

Gygax's XP-for-monsters chart also continued to be used, though slightly modified:

While there was no mention of roleplaying awards or bonuses for achieving goals, Gygax did suggest an optional special bonus of 1,000 xp for any PC that was slain but then raised from the dead.

On the subject of good roleplaying, though, Gygax added training time for advancing in level, and provided extensive rules on how to determine the number of weeks spent training, based on how well the PC performed the "natural functions" of their class, as well as acting in accordance with their alignment. Given that each week of training also cost 1500gp/level and "Poor showing with aberrant behavior" could quadruple the time spent, this was all stick, no carrot.

Additionally, Basic's "XP cap" was kept, but in a new awkward form: when a PC earned enough XP to gain the next level, they stopped earning more XP until they trained for that level. The rare DM that enforced that rule would be wise to also only award XP at the end of adventures, to avoid PCs taking a month of downtime between excursions to the plot dungeon.

Despite this minimal core system, module authors were happy to add other ad-hoc sources of XP:

• T1-4, Temple of Elemental Evil, had prisoners that could be rescued for XP rewards, as well as some small, non-magical treasures. Early encounters with prisoners weren't worth much, but later ones were nobles worth both XP and platinum.
• U1, The Sinister Secret of Saltmarsh, has an intermission in which PCs consider collected clues. PCs making deductions and taking certain actions to further the plot are awarded experience points at the DM's discretion.
• U2, Danger at Dunwater, has a half-page digression on how to calculate an XP reward for a pivotal decision made by the party.
• S1, Tomb of Horrors - even Gygax's own module contained a significant ad-hoc award for defeating the final enemy.

AD&D Second Edition (1989)

By the time Second Edition was printed, many traditions from existing groups, tournament play, published modules and other games were collected and added to the rules.

A full page in the DMG suggests possible situation that warrant XP rewards, including awards for players making the game fun (and not being disruptive), PCs surviving, players improving their play style, and PC achieving story goals. These awards are nebulous and don't include XP values.

More concretely, the existing first-edition rules were expanded, including new ideas to replace XP-for-treasure:

• XP for monsters included monsters killed, captured, routed, forced to surrender, or even persuaded to accept terms all count.
• XP for treasure was limited only to Rogue characters.

Additionally, per-class awards were somewhat codified:

Now, with the exception of the Rogue, characters could expect to earn most of their XP from defeating monsters, taking specific in-class actions (presumably while defeating monsters) and nebulous ad-hoc XP bonuses.

D&D Third Edition (2002)

3e changed everything about levels and XP. For starters, the XP required to gain a level was standardized across all classes at 1,000XP per current level above what you needed for your current level.

This is a drastic reduction from prior editions, which doubled total XP needed every level for most levels, then settled into 100,000xp or more per level after.

To compensate, XP calculations depend heavily on the PC's current level; one ogre (CR 3) against a party of four 1st-level PCs earns each of them 225xp (23% of level 2), while the same ogre against a party of four 5th-level PCs is only worth 188xp (4% of level 6). Furthermore, this causes lower-level party members to earn more XP and catch up to the average over time.

The DMG also provides three other means of earning XP without slaying (or defeating) monsters. It refers to these as "Story Awards".

• Non-combat encounters that are hazardous also have Challenge Ratings based on how dangerous they are. A trap might be CR3, just like that Ogre, if it is roughly as likely to cause injury or death.
• Mission goals earn XP rewards as well, though the specifics are left vague: The mission award should be more than the XP for any single encounter on the mission, but not more than all standard awards for encounters for the mission put together.
• Roleplaying awards are left up to the DM, but a suggestion of 50xp per character level is made. Due to the change in the XP-per-level chart, this is identical to 1/20th of the XP needed for the next level, as in Basic's Rules Cyclopedia.

However, there's an important note about these Story Awards; the DM is advised to either halve or remove the "Standard Awards" (that is, XP for defeating monsters) if Story Awards are used:

Don’t simply add story awards to standard awards (even if you compensate by giving out more treasure as well) unless you want to speed up character progression.

D&D Fourth Edition (2008)

4e squashed the XP chart further; there's a complicated algorithm, but the short version is that each new level requires just a little more additional XP than the last one, and that extra amount doubles each half-tier.

XP for encounters is fixed, with a standard monster of a given level granting 1/10th the XP a PC of that same level needs for the next level. So a level 3 Ogre is always worth 150XP (assuming a "standard" Ogre) regardless of PC levels.

Non-combat encounters with risk (traps, puzzles, etc) are counted as monsters defeated based on the type of Skill Challenge they represent. Skill Challenges are treated as combats, complete with initiative, and consist of one or more party members rolling skill checks, trying to collect a set number of successes before collecting a set number of failures. Published modules treat these as encounters, just like monsters, and specify their XP rewards for success, as well as consequences for failure.

This did not help defend 4e from accusations of being a tabletop MMO.

D&D Fifth Edition (2014)

5e modified the XP-per-level chart again, squishing the base significantly but bringing back a (somewhat) geometric progression similar to 3e's.

According to the DMG, this should work out to roughly one session (not adventure!) per level up to level 3, 2 sessions per level to level 4, and then 2-3 sessions per level thereafter. This is drastically faster than any prior edition, but is balanced by a slightly shallower power curve; 5th-level PCs are no longer superheroes when compared to 1st-level PCs as in any edition through 3.5.

Meanwhile, the XP-for-monsters works the same as 5e: monsters have pre-printed XP values, you add up the XP for the encounter and divide it among the PCs that participated.

Non-combat challenges are built like combat challenges, using the same rules to estimate the danger and consequences for failure, and award XP in the same way as combat encounters.

Additional awards can be made at milestones throughout an adventure and at its end, treating minor milestones as "easy" encounters and major ones as "hard" (there's encounter-building rules explaining difficulty levels).

Ad-hoc awards for decision making or good roleplaying are notably absent; a clear design goal of rewarding XP for overcoming challenges was closely adhered to. Given the purported "three pillars" design goals of Socialization, Exploration and Combat, the XP reward system feels under-developed.

Summary

Only recent editions of the game have been motivated to focus, through XP rewards, primarily on killing stuff. Basic, 1e, 2e and to some extent 3e have codified (or even enforced) sources of XP other than killing monsters; from acquiring treasure to roleplaying to accomplishing goals, older editions rewarded non-combat play and intelligent problem solving, often to a much greater extent that defeating monsters.

After 3.5 (including 3.5 to some extent), winning combat encounters became the primary means of gaining levels.