Evans became involved in Weatherman, a group that derived from SDS. She organized and led many Weatherman actions. Following the Greenwich Village townhouse explosion that killed three Weatherman members (Ted Gold, Diana Oughton, and Terry Robbins), Evans was one of the Weatherman members who chose to go underground in 1970. During her membership in the Weather Underground Organization, Evans provided safe housing for members of the Weather Underground Organization and by providing funding for their assumed identities. She generated these funds through her participation in various robberies. Evans also participated in the May 19th Communist Movement, a group that included some former members of the Weather Underground Organization.