A key aspect of social norms is which behavior is considered appropriate. Here we examine appropriateness ratings in the domain of everyday behavior. Our aim is to explain why certain behaviors are overall less appropriate. Drawing on theories of moral preferences, we hypothesize that this is due to behaviors having different potentials for producing externalities and internalities. In a preregistered study, American participants rated 37 different everyday behaviors on their potential for negative externalities (being loud, being aggressive, taking up space) and positive internalities (pleasurability). The behaviors were also rated on their appropriateness in a range of common situations. As hypothesized, differences between behaviors in these potentials accounted very well for their differences in overall appropriateness, and also for differences in changes in overall appropriateness since a similar study 50 years ago. This study contributes to theories of the emergence of, and variation in, social norms.