The primary goal of the project is to determine if, among families with a history of gestational diabetes mellitus (GDM) in the mother in the prior five years, a family-based multimodal health behaviour intervention (group cooking and eating/physical activity counselling, telephone-based app and text support, building of peer and within-family social support for health behaviour change) will lead to reductions in post 75g glucose load serum glucose values in mothers and fathers. The previous MoMM pilot study demonstrated an 8% reduction in mothers, similar in magnitude to that observed in a large diabetes prevention trial conducted among adults with impaired glucose tolerance (Tuomieltho et al, N Engl J Med 2001). MoMMii will ascertain if expansion to a family-based approach amplifies effects in mothers and demonstrates impact in fathers and children. Thus, MoMMii will shift the focus from the mother to the family. A systematic review and meta-analysis showed diabetes risk to be shared between spouses (Leong et al, BMC Medicine, 2014). GDM also confers higher risk for insulin resistance and overweight in offspring. Thus, this project plans to create a collaborative home environment that facilitates choices consistent with diabetes prevention for all family members. Sixty-six families will be recruited through GDM clinics at McGill University Health Centre and other centres. Five in-person sessions (meal preparation training, eating and physical activity counselling) will take place once a month at the PERFORM Centre, Concordia University. Each session will involve discussion of strategies to achieve healthy eating, hands-on meal preparation, and group-based physical activity. Sessions will engage couples as well as mothers and fathers separately. 'Healthy living' concepts will be integrated into the on-site childcare structure (meal preparation, games, videos). The intervention team will include a dietitian and kinesiologist. A health coach will facilitate networking among participating families and development of lay group leaders to sustain health behaviour changes between sessions and post program. Outcomes will be evaluated in mothers, fathers (e.g., fasting and post load glucose and insulin resistance measures, fruit/vegetable intake, step counts, eating behaviours, blood pressure) and offspring (dietary/physical activity habits).