It happened inside the Barnes & Noble bookstore on West Hillsdale Boulevard on Sunday June 23 at about 3 p.m.
Officials say the suspect approached the victim while she was in the children's book section and then led herself to a more secluded corner of the store. Police say he then exposed himself and had inappropriate contact with the victim.
Video footage of the suspect was captured on the store's surveillance cameras.
The suspect is described as a white male in his 50s, approximately 6'0" tall, wearing a fishing hat, sunglasses, and tan cargo pants.
He was last seen getting into a dirty black or grey four-door car parked in the store parking lot.
Anyone with information is urged to contact the SMPD Investigations Bureau at 650-522-7650 or the SMPD Secret Witness hotline at 650-522-7676.