PropositionsSaving money by behaving pro-environmentally often leads to expenses that reduce the positive environmental impact of the original behavior. (this thesis) People behave pro-environmentally when their motivation is strong enough for the behavior to feel easy. (this thesis) Social psychologists should be involved more in testing the impact of policies on behavior.Social changes require both system change and individual change.Transferring insights from science to practice takes as much time and effort as doing the research itself.Academic publishers should be non-profit organizations to balance the effort and revenues for researchers and the public.If the Dutch government wants to encourage research by external PhD researchers ('buitenpromovendi), it should provide childcare benefit to those with children.Propositions belonging to the thesis, entitled.