When does a character gaining a level in a new class get the features of that class?

Question

When does a character gaining a level in a new class get the features of that class, according to the RAW of DnD3.5?

In my interpretation, when your character, who already has levels in some other class, becomes a LV1 something (picks up a completely new class), she or he gains access to all the features, bonuses, skills, spells, etc. of the first level of something instantly. This may seem illogical -- and some DMs may very well decide to circumvent this, opting to "play through" the transition -- but the RAW seems to work this way, in accord with the inherent abstraction level of the system.

Is my interpretation correct? If not, how does this work according to the RAW?

Answer 1

Rules-as-written, when you gain a level in a new class, you immediately gain all all the class benefits that a first-level character would, except that you do not gain 4x skill points, maximum hit points for your hit die, starting gold, or starting equipment.

Rules for adding a second class appear in the Player's Handbook, p.59:

As a general rule, the abilities of a multiclass character are the sum of the abilities of each of the character's classes.

The character gains the 1st-level base attack bonus, base save bonuses, class skills, weapon proficiencies, spells, other class features of the new class, hit points of the appropriate Hit Die type, and the new class's number of skill points gained at each additional level (not that number x 4, as is the case for a first-level character).

The DM can require players to undergo special training before gaining a new class, but the rules don't suggest delaying acquisition of class abilities once the level is gained:

The DM may restrict the choices available based on the way or she handles classes, skills, experience, and training. For instance, the character may need to find a tutor to teach him or her the way of the new class. Additionally, the DM may require the player to declare what class the character is "working on" before he or she makes the jump to the next level, so the character has time to practice new skills.

Answer 2

The Dungeon Master’s Guide suggests that a DM may require players to role play the acquisition of new abilities, but this is always before leveling up. Furthermore, you cannot use any of the abilities “for real” at all until you actually have leveled up.

In effect, you get all of these abilities at once in mechanical terms, but you are assumed to have been working on them for the previous level and they’ve all just “come together” for you as you level up. Levels are inherently an abstraction: instead of gradually gaining features, they’re all lumped together. That doesn’t mean the character isn’t improving all the time. We effectively just get a coarse-grained “slideshow” of this improvement due to leveling.

Answer 3

D&D 3.5 doesn't specify any kind of gradual process for gaining hit points, skills, class features, &c. You learn them all at once, at the moment you gaining a level.

I'm not sure what to cite to prove a negative here, really: as a matter of mechanics, the core books simply don't have any special rules for gradually gaining class abilities, when you multiclass or otherwise. All of the level-up changes are "locked in" together, at the moment you level.

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As for the issue of "logic," D&D's level-based system isn't designed to strongly reflect reality in the first place. Classes and levels are already a massive, purposeful abstraction of a character's abilities. Trying to parcel out level-up benefits piecemeal just creates the opportunity for lots of confusion and mistakes on your character sheet.

The main allowance D&D3.5 makes for "realism" in leveling is giving the GM leeway to require downtime or training before a level-up. The book suggests you narrate training for new abilities before you've gained your level; you don't actually get to enjoy the mechanical benefits until you level, however.