Purpose: To explore familial eating patterns and weight-related concerns among families of adolescent girls with type 1 diabetes mellitus (DM) and to examine associations with disordered eating behaviors among the girls. Methods: Interviews were conducted with 30 adolescent girls (ages 13-20 years), who had DM for at least 1 year, and separately with their parents. Eighty-four percent of the girls were Caucasian, 13% were African-American, and 3% were Hispanic. The sample included 15 girls who reported (on a questionnaire) engaging in disordered eating behaviors (DE) and a matched comparison group of girls who reported no disordered eating (Non-DE). The semi-structured interview questions focused on adolescent and parent perceptions of the impact of DM on family roles, relationships, and routines, as well as who does what in managing the DM. A content analysis of the interviews identified themes regarding family meal patterns and weight-related issues. Results: Although variation was found, more than one-half (57%) of the families were classified as having a high level of meal structure (e.g., frequent family meals). Families with DE girls were more likely to be classified as having a low level of meal structure (e.g., infrequent family meals) than families with Non-DE girls. Weight concerns (e.g., at least one member having a high desire to lose weight). The prevalence of families with a parent engaging in behaviors to lose weight and/or making negative comments about eating or weight was higher in families of DE girls than Non-DE girls. The combination of low family meal structure and high familial weight concerns was much more prevalent in families with DE girls (58%) than in families of non-DE girls (7%). Conclusions: Interactions around food and weight appear common in many families of adolescent girls with DM. Whereas frequent family meals may help to defend against disordered eating in youth with DM, family weight concerns and behaviors appear to be risk factors for disordered eating. (C) Society for Adolescent Medicine, 2004.