Strategies for increasing worker involvement in health and safety are widespread and have received emphasis in various OSHA reform proposals; however, much remains unknown about the effectiveness of these strategies. This paper draws on a survey of more than 400 New Jersey members of the American Industrial Hygiene Association (AIHA) and the American Society of Safety Engineers (ASSE) which addressed a broad range of issues relating to health and safety conditions and practices, including the use of worker or labor/management health and safety committees (HSCs) and worker health and safety representatives. Stepwise discriminant analysis was used to explore the relationships between effective participation and variables which describe worksites and potential health and safety resources and barriers. Effective strategies for involving workers appear to be conditional on a number of variables, most importantly on worker activism and the effective use of formal union negotiations. Findings are consistent with studies from both the U.S. and abroad which emphasize the role of unions in shaping opportunities for effective worker participation.