The authors examined environmental concern and involvement of individuals in two voluntary associations, the International Mountain Bicycling Association (IMBA) and National Off-Highway Vehicle Conservation Council, Inc. (NOHVCC). Environmental concerns were assessed using the New Environmental Paradigm (NEP). When compared, results from 10 of 12 NEP items were found to be significantly different. The IMBA group scored higher on the NEP, showing a greater level of agreement on environmental concern. IMBA respondents were also more involved with environmental organizations than the NOHVCC sample. The study results suggest that the level of environmental concern and involvement differs for those who are in specific voluntary associations and who choose specific outdoor activities. Implications are discussed for educators and resource managers. (Contains 3 tables.)