My daughter, who is 5 and has been diagnosed with autism, has a vocabulary of only about five words now. (When she was 1-year-old she had a vocab of 14 words.) We knew she had communiation skills but she had lost the ability to express herself verbally. Currently her pre-school, and at home, are using PECS, consistently. It was slow starting, but once she caught on she's adapting it in her own way. Many times now, when she does not have a picture to show us what she needs/wants, she will go find a source (video, book, object), point to the image she's trying to convey, and make eye contact to get acknowledgement that we recognize what she's trying to communicate. PECS has really helped ameliorate her frustrations with communicating. We're also finding that she's associating the printed words to the images and I feel that she may be able to read/write someday. I think she's happier because now she has some control over what she needs/wants. Hope relating our successful use of PECS may help convince your client's parents and school to give it a try.