This investigation compared online and paper administration of self-report measures of weight and shape concerns, mood, weight and height. The former was designed as a screening instrument for adolescent students to determine risk for eating disorders. Participants were female sophomores (N = 74) from a San Francisco Bay area private high school. A counterbalanced designed was used to control for order effects. Four classes were randomly assigned to one of four conditions: (1) online–paper; (2) paper–online; (3) online–online; and (4) paper–paper. Participants completed self-report questionnaires twice, online and/or on paper, separated by 1 week. Agreement between online and paper assessment of weight and shape concerns and BMI ranged from 0.73 to 0.97 and 0.80 to 1.0, respectively. Agreement for positive mood ranged from 0.58 to 0.85 and negative mood from 0.59 to 0.82. Mean scores for weight and shape concerns and mood variables were significantly lower at the second testing. Online and paper assessment of weight and shape concerns was significantly correlated. However, there was a significant time effect. Mood was less stable and correlations between the two modes of self-report were less correlated. Online assessment may be beneficial and appropriate for many settings.