Research on union renewal often cites a critical role for lay activism. This study examines determinants of activism and activism intentions among a broadly representative sample of U.S. union members. Hypotheses are developed from theory and previous research on union commitment and participation. Results for current activism are generally consistent with prior work. Extending the model to future intentions to help with organizing, an interesting contrast is that pro-union attitude influences appear much more important than do union instrumentality perceptions. This suggests that “covenant” rather than “exchange” concerns are more salient for this form of activism. Findings for ideological orientation support this interpretation.