Environmental policy-makers increasingly emphasize consumers' responsibility for environmental side effects of their acts, but is this justified? This paper investigates which is the most important limiting factor for sustainable consumption: (a) the extent to which consumers assume responsibility for their acts or (b) structural conditions determined by governments? In field experiments with large samples of ordinary consumers, the behavioral effects of perceptions of responsibility/personal moral norms and of altering an important structural condition are quantified by measuring a relevant behavior before and after a change in the structural condition. Study 1 investigates the effects of implementing a collection scheme for source-separated kitchen waste and Study 2 the effects of providing a free month travel card for public transport to car-owners in a metropolitan area with a well-developed public transit service. The results suggest that there is often more to gain from changing structural conditions to be more facilitating for the desired behavior than from a campaign targeting consumer feelings of responsibility.