Background: It is presently unknown whether behaviorally oriented, theory-based nutrition education from a Western context could be effective for improving healthy eating behavior and its psychosocial determinants among Russian children. Effective nutrition education delivered in summer programs could potentially impact dietary patterns and play an important role in efforts to reduce childhood obesity. We hypothesized that nutrition education including an additional behavioral skills component would be superior to nutrition education without this component and that boys and girls would differ in their response to nutrition education.Methods: Boys (n = 19) and girls (n = 21), aged 8-12 years, were assigned to one of two conditions receiving 15 daily sessions of behaviorally oriented, theory-based nutrition education. One condition received an additional skills training component, including activities such as snack preparation, role-playing, and games. An innovative objective measure was used to assess change in healthy snack choices. Psychosocial determinants of healthy eating (i.e., healthy eating knowledge, fruit self-efficacy, vegetable self-efficacy, healthy eating attitudes, and fruit and vegetable enjoyment) were assessed via questionnaire. Contrary to our hypothesis, there were no significant differences in any change scores by nutrition educational condition (p > 0.05). Among the six outcomes, there was one significant sex difference for fruit and vegetable enjoyment change score (p = 0.002), as girls showed a larger increase in enjoyment over time compared to boys, and the overall nutrition education effects differed by sex (F = 3.03, p = 0.019). Conclusions: Nutrition education, with or without behavioral skills training, was associated with improved healthy snack choices, healthy eating attitudes, and knowledge, but the impact differed by sex. Future research should evaluate the long-term impacts of behaviorally oriented nutrition education among Russian boys and girls.Trial registration: ClinicalTrials.gov NCT03077464