The authors evaluated the environmental education program of the Golden Lion Tamarin Association in Brazil by comparing results of a 2001 survey with baseline data from 1986. Responses of 666 residents and results from 4 focus groups revealed an increase in public support for the tamarin and its habitat and an increase in general environmental knowledge. The evaluation identified gaps in knowledge about the biology and conservation status of the tamarin and gaps in women's participation in the education program. (Contains 4 tables.)