Deontic assertions concern what people should and shouldn't do. One sort concern moral principles, such as: People should care for the environment; and another sort concern social conventions, such as: People should knock before entering an office. The present research examined such deontic assertions and their corresponding factual assertions, such as: People care for the environment and People knock before entering an office. Experiment 1 showed a correlation between emotions and beliefs for both sorts of deontic assertion, but not for their factual counterparts in which the word “should” had been deleted (as in the preceding examples). Experiment 2 showed that changing the pleasantness of participants' emotions about social conventions changed their strength of belief in them. Experiment 3 showed conversely that changing the participants' strength of belief in social conventions changed the pleasantness of their emotions about them. These results corroborate the mental model theory of deontic assertions, which postulates that emotions and beliefs about deontics depend on parallel systems that interact with one another.