Thin-ideal (or media) internalization is an important eating disorder risk factor that has become a central target of many prevention programs. However, evidence for its valid assessment in young, mixed-gender, adolescent samples is limited, and the current study is the first to explore the psychometric properties of the 30-item Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3; J. Thompson, P. van den Berg, M. Roehrig, A. S. Guarda, & L. J. Heinberg, 2004) in a nonadult community sample. Two samples of Grade 8 students (M age = 13.68 years), totaling 680 girls (N = 332) and boys (N = 348) completed the SATAQ-3 and other measures, whereas a smaller sample (N = 123) of Grade 10 girls (M age = 15.01 years) served as a comparison group for supplementary analyses. Principal component analyses (PCA) with data from Sample 1 (N = 201) revealed 4 factors with eigenvalues greater than 1.0, similar to the original authors' structure but with some cross-loading occurring between the Pressures and Internalization-General scales. Confirmatory factor analyses (CFA) were conducted with data from Sample 2 (N = 479) on the factor solution found in the PCA. The model did not fit well, leading to further revisions based on removal of cross-loading items and CFA modification indices, resulting in a 19-item, 4-factor solution with acceptable fit. Examinations of validity and reliability were generally acceptable. The overall findings suggest that an abbreviated version of the SATAQ-3 might be more appropriate than the original version with young-adolescent, mixed-gender audiences. Further examinations of the psychometric properties of the SATAQ-3 with this demographic are indicated. (Contains 1 figure and 5 tables.)