OP, I just posted looking for someone for my pre-schooler in MD for selective mutism. Here is one response I received that might help you:

Alison Gardner at Family Compass in Reston, VA specializes in selective mutism. I know it is far but she is truly wonderful.

(We ended up seeing Karen Prince in Kensington.)

or here:

https://www.facebook.com/#!/groups/MD.DC.PA.SelectiveMutismSupport/

You might ask here:

http://health.groups.yahoo.com/group/Selectivemutismsupportgroup/

Any recommendations for a therapist, preferably in Northern VA for a teen diagnosed with selective mutism? I was just going to add... someone patient and willing to work with extreme shyness and reticence but thats the whole point! Thanks in advance.