D&D 3E/3.5 How backwards compatible to 3.5 is Pathfinder?

[Salthorae]

Pathfinder Conversion Guide

Here is the link to the guide, it's pretty good guide and has lots of the answers you'll want. I've played both 3.5 and Pathfinder pretty extensively, also just got run in a game that was people making characters from both Pathfinder AND 3.5 rule sets and it worked pretty well I thought.

Some of the base classes are underpowered in 3.5 vs Pathfinder, but other than that, not much really. Your BBEGs could probably use some sprucing up, but the monsters themselves should be fine as they are from a 3.5 module.

There are some rules you should check up on like CMB/CMD and make sure you look at the updated Sneak Attack for monsters (basically everything except Incorporeal can be Crit'd and Sneak Attacked)...

They are very compatible though!

 

[Kaodi]

In terms of adventure design, I kind of suspect that if you are converting 3e/v3.5 material to Pathfinder, you might have a bit more even experience if your PCs stick to the Pathfinder Core, since the classes are basically the same, though tweaked. Might not be that big a deal though.

 

[am181d]

and make sure you look at the updated Sneak Attack for monsters (basically everything except Incorporeal can be Crit'd and Sneak Attacked)...

That's one rule I'm definitely grabbing for 3.5. I had them fighting undead last week and the lack of Crits and Sneak Attacks was just less fun. Every time somebody rolled a 20 there was the immediate rush of satisfaction followed immediately by deflation.

(Doesn't help that Fantasy Grounds is set to auto-roll the Confirm roll.)

 

[lucek]

I've played with D20 material in PF and vice versa. It works 90% but when that last 10% happens boy does the game break. For 1 PF monsters are a bit stronger. Like 1 or 2 levels stronger then creatures from 3.5. Another thing some spells were changed slightly making them completely broken when translated between game. Black tentacle for example.