Objective: Frequent self-weighing is recommended in weight loss interventions and may prevent weight gain. However, concerns regarding the associations between self-weighing and eating disorders have been expressed and the relations between self-weighing and weight gain/eating pathology have not been examined prospectively. We tested whether (a) frequency of baseline self-weighing in college students with weight concerns predicted weight change over 2-year follow-up, (b) this relation was moderated by eating disorder symptoms, and (c) self-weighing predicted future eating disorder symptoms. Method: Data were merged from two trials evaluating obesity/eating disorder prevention programs in 762 students (Mage = 18.7; 86% women). Participants reported how often they weighed themselves at baseline; body mass index (BMI) and eating disorder symptoms were assessed over 2-year follow-up. Results: Baseline self-weighing predicted weight gain, with more frequent weighers experiencing greater gains (i.e., +0.8 of BMI) over follow-up. This relation was moderated by the frequency of binge eating but not weight/shape concerns or compensatory behaviors; the combination of more frequent self-weighing and binge eating was associated with greatest weight gain (+1.6 of BMI). More frequent weighers also reported higher onset of compensatory behaviors, relative to non-self-weighers (odds ratio = 3.90, 95% confidence interval [1.76, 8.75]). Conclusions: Young adults who weighed themselves more frequently had greater weight gain than those who self-weighed less frequently, especially those who engaged in binge eating, and were at risk for future unhealthy compensatory behaviors. Findings suggest that frequent self-weighing may have negative effects for some young adults, and that relations between self-weighing and weight control outcomes require further investigation.