The present study sought to examine the influence of introjected beliefs on individuals’ vulnerability to counterattitudinal arguments. University students’ reasons for engaging in proenvironmental behaviors were assessed prior to their reading excerpts from a counterattitudinal article. The excerpts were written by a personally attractive or unattractive author and contained either weak or strong arguments against recycling. Our results show that individuals who were highly introjected about recycling (e.g., “I recycle because I would feel guilty if I didn't”) were influenced by the personal attractiveness of the source but not by the strength of the specific arguments. Specifically, a thought-listing procedure revealed that introjection was associated with generating more favorable thoughts and fewer counterarguments about the anti-recycling message when the author was personally attractive than when he was unattractive.