Individuals with appearance concerns engage in "safety behaviors" (SBs) aimed at checking, hiding, fixing, and reducing threat associated with their perceived flaw in appearance. Appearance-related SBs are important in contemporary accounts of body dysmorphic disorder (BDD), though they are also relevant to social anxiety (SAD) and eating disorders. The present study examined the extent to which appearance-related SBs contribute to the development of disorder-specific symptoms and maladaptive cognitions. Female undergraduates without clinically elevated appearance concerns (N = 99) were randomly assigned to 1 week of (a) increasing the frequency and duration of appearance-related SBs (SB+), (b) decreasing these behaviors (SB-), or (c) a control in which they increased their academic studying behaviors. Generally, SB+ participants demonstrated greater BDD symptoms, SAD symptoms, body dissatisfaction, disorder-relevant threat interpretations, beliefs about the importance of appearance, and reactivity to an in vivo appearance-related task following the manipulation, relative to the other groups, with some exceptions. The SB- and control conditions largely did not differ from one another in these outcomes. SB+ participants also reported greater anxiety and depressive symptoms postmanipulation relative to other conditions. Groups no longer differed from one another at a follow-up assessment. Overall, these findings suggest that engagement in appearance-related SBs may play an instrumental role in symptoms and maladaptive cognitions across a range of disorders. (PsycINFO Database Record (c) 2018 APA, all rights reserved).