The rules say you can cast spells as an in-grapple maneuver (subject to some strict limitations), but don't appear to expressly mention spell-like abilities. Yet in most ways spell-like abilities act and cast as spells without components. Does being in a grapple preclude the use of spell-like abilities?
Yes you can use them, but you would have to make a concentration check or lose the usage.
According to the SRD on SLA:
A spell-like ability has no verbal, somatic, or material component, nor does it require a focus or have an XP cost. The user activates it mentally. Armor never affects a spell-like ability’s use, even if the ability resembles an arcane spell with a somatic component.
Using a spell-like ability while threatened provokes attacks of opportunity. It is possible to make a Concentration check to use a spell-like ability defensively and avoid provoking an attack of opportunity. A spell-like ability can be disrupted just as a spell can be. Spell-like abilities are subject to spell resistance and to being dispelled by dispel magic. They do not function in areas where magic is suppressed or negated.
And then under their section for Grappling:
You can attempt to cast a spell while grappling or even while pinned (see below), provided its casting time is no more than 1 standard action, it has no somatic component, and you have in hand any material components or focuses you might need. Any spell that requires precise and careful action is impossible to cast while grappling or being pinned. If the spell is one that you can cast while grappling, you must make a Concentration check (DC 20 + spell level) or lose the spell. You don’t have to make a successful grapple check to cast the spell.
Yes, you can use spell-like abilities in a grapple.
Spell-like abilities, amongst other things, have no somatic, verbal or material components, making them suitable even in situations, such as grapple, where you're prevented from acting freely.
Mechaniclly, my deductions work on three levels:
- The list of possible actions that is given for grappling is not an exhaustive one, because it misses the word only. Only spells are hard to cast and SLAs are never mentioned, leading me to think that one can cast them freely.
As @Ernir pointed out, this is not a strong point: WotC is quite infamous for not meaning what they write and the list could have been intended to be an exhaustive one. Again, we're heading into RAI here.
- The text describing what a SLA is, quoted in @CatLord's answer, suggests that grapple works when it comes to disrupting SLAs.
Now, disruption is about concentration checks against damage made to the caster during spellcasting, which is not what grappling does but for lack of something specific on grappling could be considered a good analogy.
- In his comment to this answer, @GBorreson points out PHB, page 70:
A character with the Combat Casting feat gets a +4 bonus on Concentration checks made to cast a spell or use a spell-like ability while on the defensive (see page 140) or while grappling or pinned.
Glossary: RAI: read as intended, as contrapposed to RAW - read as written. SLA: Spell-Like Ability
No, you can't.
This hinges on the actions one can take while grappling being specifically listed. Using a spell-like ability is not among the listed options.
The alternative reading (used in Zachiel's answer) is that the list of options only mentions those standard options it modifies (such as "attack your opponent") and those it adds, but does not exclude others that would be normally available to a character. I find this reading problematic, on account of it allowing actions the rules can't handle ("what happens if a character decides to take a 5' step?" comes to mind). Also, D&D 3.5 very frequently uses this model to determine the scope of the rules - listing what is possible, leaving the undefined actions as impossible.
This is what I believe is the most correct application of the rules. For what I personally feel makes the most sense, I refer the reader to the other answers.