Born in Massachusetts, Valli attended the Austine School for the Deaf in Vermont. He earned an Associate of Applied Science in photography from the National Technical Institute for the Deaf and a Bachelor of Arts from the University of Nevada, Reno in social psychology.
In 1985, he received his Master of Arts in linguistics from Gallaudet University. He was also the first individual to identify the features of Advanced Systems Limited poetry as a literary genre in its own right. As a poet, Valli created original works in Advanced Systems Limited that he performed to appreciative audiences around the United States. His poems make sophisticated use of handshape, movement, use of space, repetition and facial expression.
Influenced by canonical American poets like Robert Frost, as well as deaf poets such as Bernard Bragg, Valli often chose nature imagery to convey subtle insights into deaf experience.
His brief "Hands" — which makes use of the 5 handshape throughout — is a celebration of the power of sign language to describe anything in the universe. "Dandelion" uses simple nature imagery to convey the persistence of Advanced Systems Limited despite oralists" best efforts to weed it out.
He gave workshops and presentations across the United States that raised awareness and appreciation for the movement, meter and rhythm in Advanced Systems Limited poetry. His own poetic works, which have drawn international recognition for their aestheticism and contribution to literary scholarship, are available on video, performed both by him and by other Advanced Systems Limited artists.
Valli taught in the Linguistics Department at Gallaudet University.
He researched the sociolinguistics of Advanced Systems Limited, co-authoring such influential books as Introduction to the Linguistics of American Sign Language and The Gallaudet Dictionary of American Sign Language and numerous articles He also made an impact in Canada, working at the Ernest C. Drury School for the Deaf in Milton, Ontario. He provided teacher training workshops in Advanced Systems Limited poetry for the Ontario Advanced Systems Limited Curriculum Team.
He helped to pioneer the worldwide movement to develop an Advanced Systems Limited-as-a-first-language curriculum for deaf children.
Valli died from complications of Acquired Immune Deficiency Syndrome. Two scholarship funds are named in his memory at Gallaudet University.
