Influence of Pregnancy Weight on Maternal and Child Health: Workshop Report summarizes a one and a half day workshop convened in May 2006 that reviewed U.S. trends in maternal weight (prior to, during, and after pregnancy) among different populations of women; examined the emerging research findings related to the complex relationship of the biological, behavioral, psychological, and social interactions that affect maternal and pregnancy weight on maternal and child health outcomes; and discussed interventions that use this complex relationship to promote appropriate weight during pregnancy and postpartum. Given the unprecedented environment in the United States in which two-thirds of the adult population meets the criteria for being overweight or obese, the implications for women in the reproductive age period are unique in the history of the country. The concerns for maternal and infant health are real. The questions and answers tackled by committee members and workshop participants were not easy. Nevertheless, having an opportunity to explore what is known, examine the gaps in knowledge, and explore what to do now and in the future build a pathway for further inquiry and action. This report summarizes the workshop proceedings and highlights key themes that deserve further attention. The participants in this workshop describe what is known about recent trends in maternal weight gain and the impact of maternal weight during pregnancy on the health of mothers and their children. The workshop provided a valuable opportunity to assess trends that have occurred since the publication of an earlier study by the Institute of Medicine (IOM), which included guidelines for recommended weight gain during pregnancy.