Hypotheses about possible mechanisms for spillover processes between pro-environmental behaviors were developed and tested by means of structural equation modelling. Data were collected by means of telephone interviews with a representative sample of 1,002 Danish adults. Personal norms concerning recycling and packaging waste prevention were found to be rooted in the same more general, internalized values. Further, a predicted positive spillover effect from recycling to packaging waste prevention was confirmed. However, whereas a positive spillover effect from recycling to personal norms concerning packaging waste prevention was predicted, the reverse was found. Neither was it confirmed that performing an environmentally friendly behavior made attitudinal and more distal antecedents of related behaviors more predictive of the next step in the assumed causal chain.