[d20 modern] advanced class requirements?

[Froogleyboy]

Okay, if there is an advanced class that calls for BAB: +3 and I have +2, when I level up, do I have to go through another basic class level or can I go in to the advanced class

[The Rose Dragon]

You have to take another basic class level.

You take your level, then you take the benefits of the level. You must meet all the prerequisites of an advanced class to be able to take the first level. Ergo, you have to have +3 BAB from other sources before you can take the first level.