I'm a speech-language pathology student, and yes, apparently we (SLPs) are able to make the AUTISM diagnosis. I assume this would include Asperger's. However, the SLPs who are my prefessors often admit that they would not be comfortable actually making the diagnosis and would prefer to refer the person on to another professional.
This quote is directly from ASHA, the SLP governing association: (http://www.asha.org/policy/PS2006-00105/)
Quote:
Appropriate roles for speech-language pathologists include but are not limited to the following:
Screening: Speech-language pathologists play a critical role in screening and early detection of individuals at risk for ASD and makes referrals to experienced professionals for diagnosis and intervention services.
Diagnosis: Speech-language pathologists who acquire and maintain the necessary knowledge and skills can diagnose ASD, typically as part of a diagnostic team or in other multidisciplinary collaborations, and the process of diagnosis should include appropriate referrals to rule out other conditions and facilitate access to comprehensive services.
So while I don't know any SLPs who would feel totally comfortable making the diagnosis, it is within our scope of practice.
I hope that helps!