The class system in FE7 has not changed much from FE6. In fact, it has gotten even simpler, since there are now no instances of multiple playable unpromoted classes promoting into the same promoted class. There is the case where Pirates, Corsairs (enemy only, basically the exact same as Pirate), and Brigands (enemy only) all promote into Berserker, but there is only a single playable Pirate in the game.

The main lord, either Eliwood or Hector, has their promotion locked behind a story event. The other two lords can promote with a Heaven Seal once they reach level 10 or higher. The main lord will promote regardless of level, at the end of chapter 27E or 29H.

In general, promotion stat bonuses are a bit more muted compared to FE6. This, along with the extremely lofty experience requirements for ranked runs makes it less attractive to promote very early on for most units. However, a lot of units will still greatly improve upon promotion. For example, Canas gets 4 extra AS, along with a significant amount of defensive stats; Pegasus Knights will gain a much needed 2 points of Strength, as well as 5 HP and 2 Def/Res.

Similarly to FE6, only a handful of classes in the game are only available to one gender. There are again slight differences between stat caps, promotion bonuses, base stats, and sprites.

One difference is that FE7 does not have promotion bonuses for many unused promotion paths. For example, female Nomads (there are none) would not gain any stats upon promotion in an unmodded game. However, some female prepromotes have data for promotion bonuses that are equal to the male version's. In particular, female Swordmaster (Karla) and female Paladin (Isadora) have the exact same promo bonuses as the male versions. Despite this, female Wyvern Lords do not have promo bonuses listed even though Vaida exists.

On the other hand, class paths with both genders being in the game have completely different promotion bonuses, for example Sniper (Rebecca and Wil).

This page lists all classes in FE7, organized into unpromoted and promoted classes. The differences between male/female classes are not listed here, click into an individual class to see that data along with promotion stat bonuses.