Objective: To describe the development and psychometric properties of survey measures relevant to eating, physical activity, and weight-related behaviors among young adults. Methods: Focus groups and reliability testing guided the development of the Project EAT-III survey. The final survey was completed by 2287 young adults. Results: The systematic process employed led to a psychometrically sound and developmentally appropriate survey. Test-retest reliabilities for items included on the final survey were mostly moderate to good, and Cronbach alphas were greater than 0.7 for 83% of developed scales. Conclusions: Future studies may find the systematic process used to be helpful in creating other weight-related surveys.