The last decade of research has suggested that family meals play an important role in promoting healthful dietary intake in youth. However, little is known about the structural characteristics and interpersonal dynamics of family meals that might help to inform why family meals are protective for youth. The current mixed methods, cross-sectional study conducted in 2010-2011 includes adolescents and parents who participated in two linked population-based studies. Participants included 40 parents (91.5% female) and adolescents (57.5% female) from the Minneapolis/St Paul, MN, area participating in EAT (Eating and Activity Among Teens) 2010 and F-EAT (Families and Eating and Activity Among Teens). The structural (eg, length of the meal, types of foods served) and interpersonal characteristics (eg, communication, emotion/affect management) of family meals were described, and associations between interpersonal dynamics at family meals and adolescent body mass index and dietary intake were examined via direct observational methods. Families were videorecorded during two mealtimes in their homes. Results indicated that family meals were approximately 20 minutes in length, included multiple family members, were typically served family style (70%), and occurred in the kitchen 62% of the time and 38% of the time in another room (eg, family room, office). In addition, significant associations were found between positive interpersonal dynamics (ie, communication, affect management, interpersonal involvement, overall family functioning) at family meals and lower adolescent body mass index and higher vegetable intake. These findings add to the growing body of literature on family meals by providing a better understanding of what is happening at family meals in order to inform obesity-prevention studies and recommendations for providers working with families of youth.