I want to play a bunch of 1st Edition AD&D modules in my 2nd Edition campaign, but I have only ever played 2e so my knowledge of 1st Edition is only very basic.

What would I need to do to make a conversion from the older AD&D to 2E? I am thinking monster stats, and so on.


The differences between AD&D 1st edition and AD&D 2nd edition is very small 2nd edition is merely a polished version of 1st edition so you shouldn't really have a problem using 1st edition modules in 2nd edition.

I asked a similar question here the answer by aramis offers a comprehensive detailing of the differences between the editions which might be of some assistance.

Also I took a look at the differences in the stat blocks from AD&D 1st and AD&D 2nd editions and they are basically identical, the 2nd edition stat blocks are just a little more organized.

I haven't played 2nd edition but I have used 2nd edition campaign settings and adventure modules in my AD&D 1st edition campaigns and I had absolutely no trouble using them, there wasn't anything i found incompatible. I basically did what your trying to do but in reverse and it worked out fine.

  • \$\begingroup\$ Thanks for the comprehensive answer I really appreciate your response, I will look at the link you give. \$\endgroup\$ – user7920 Apr 16 '13 at 8:22

If running a published module...

NPC's: change assassins to multi-class or dual class fighter-thieves. Change Cavaliers to Fighters. Add relevant Proficiencies. Look up Thief Skills in the table in the DMG in the section on creating classes.

Monsters: look up the THAC-O, refigure XP based upon the DMG tables.

Magic Items: replace any abilities that you cannot find matches for.

If the monster in the module isn't in your Monstrous Compendium and isn't detailed in the module (there are a few cases), simply replace it with something similar.

  • \$\begingroup\$ Thanks for your response, I am running published modules mixed with my own "Side Quest" adventures so I will make the changes you suggest. I really appreciate the time you have taken to respond. \$\endgroup\$ – user7920 Apr 16 '13 at 8:24

I used to do this all the time. 1st edition and 2nd edition were so similar that I used any module any where, including what are now called BECMI modules. The stat block might be in different orders but it was all the same stuff. I knew the rules well enough and I ran it. To me it was all backwards compatible until 3rd edition came out.

2nd edition and BECMI both used THAC0. 1st Edition would say attacks as F1 or C2 or whatever. So there you go. F1 is Fighter 1 so THAC0=20, C2 is Cleric 2 so use that THAC0 and so on etc. Hit Points as in the stat block whichever system it came from. Saving Throws from 1ed was the same: Monster would save as F1, F2, F3 use that. I used 2nd Edition morale as it is faster to use.

You don't need every rule and you don't need all the stats. There really is not a need to convert much of anything from 1st to 2nd, or from BECMI for that matter. They were so similar... It was intuitive to me. You can also pick and choose rules from whichever Edition you like and and ignore the other two. If one does not make sense use the other, if one is too complicated use the other, and so on.

  • \$\begingroup\$ Welcome to RPG.se! Please take a look at the tour; it's a useful introduction to the site. I gave this a bit of a polish with an edit. You might notice in particular that I removed the first sentence about it being an old thread: two things to know about the site is that it isn't a forum, and new answers are always welcome on open questions no matter the age. Take a look around and see how things work differently here and, again, welcome! \$\endgroup\$ – SevenSidedDie Apr 21 '15 at 22:41

A few differences that came to mind:

  • In 1st ed., PCs get 1 xp for every gp of treasure obtained, including magic items, seized equipment, etc. As a consequence, published modules sometimes leaned on loot to determine XP awarded. I would recommend recalculating all monster XP values and determining some additional story awards, with the award being especially high for carrying off a lot of treasure, if that's the theme of the module.
  • Magic resistance scales with the level of the caster, with listed MR applying against an 11th level caster and scaling up or down by 5% per level of difference. If there's an unfamiliar creature with magic resistance, I would suggest adjusting it to the MR scaled to the likely PC level of the caster.
  • Assassins are thieves with some fighter abilities, but also have the assassinate ability, giving an additional 50% (adjusted up or down depending of the level differential of assassin and victim) of an instant kill to any successful back-stab. For conversion purposes, assuming every assassin has a poisoned weapon (possibly scaling the poison type with the assassin's level) would maintain a similar flavor.
  • The various expansion books may be helpful, if you have access to them, as a large amount of the content originally removed in the conversion to 2nd edition reappears in the Complete Handbook series: cavaliers, monks, psionics, half-orcs, dark elves, some spells and items.
  • Dragons are mostly a bit weaker in 1st ed., so you might want to reduce the listed age category by one or two steps to maintain a similar level of challenge.
  • Magic missile weapon bonuses are cumulative with magic ammo bonuses in 1st, supposed to be averaged in 2nd, so a 1st ed magic bow+1 is equivalent to a second ed bow+2.
  • Familiars are more beneficial and a special familiar, such as an imp, can greatly increase a magic-user's power. Consider treating an MU with an imp as a level higher (part of the benefit).
  • Each level of each character class has an official name, and if an NPC is described as, say, a 'Myrmidon', that character is a 6th level fighter, and occasionally both the class and level will be omitted as redundant. Confusingly, some specialist wizard types from 2nd ed. (Evoker, Necromancer, etc.) show up as terms in 1st ed., but those refer to level designations of magic-users.
  • \$\begingroup\$ This seems to be a general list of differences between editions, but not necessarily ones relevant to converting modules, nor presented in a way that makes it obvious what to do with the information when converting modules. \$\endgroup\$ – SevenSidedDie Nov 17 '19 at 21:23

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