Objectives Excessive gestational weight gain (GWG) is a key modifiable risk factor for negative maternal and child health. We examined the efficacy of a behavioral intervention in preventing excessive GWG. Methods 230 pregnant women (87.4 % Caucasian, mean age = 29.2 years; second parity) participated in the longitudinal Glowing study (clinicaltrial.gov #NCT01131117), which included six intervention sessions focused on GWG. To determine the efficacy of the intervention in comparison to usual care, participants were compared to a matched contemporary cohort group from the Arkansas Pregnancy Risk Assessment Monitoring Survey (PRAMS). Results Participants attended 98 % of intervention sessions. Mean GWG for the Glowing participants was 12.7 ± 2.7 kg for normal weight women, 12.4 ± 4.9 kg for overweight women, and 9.0 ± 4.2 kg for class 1 obese women. Mean GWG was significantly lower for normal weight and class 1 obese Glowing participants compared to the PRAMS respondents. Similarly, among those who gained excessively, normal weight and class 1 obese Glowing participants had a significantly smaller mean weight gain above the guidelines in comparison to PRAMS participants. There was no significant difference in the overall proportion of the Glowing participants and the proportion of matched PRAMS respondents who gained in excess of the Institute of Medicine GWG guidelines. Conclusions for Practice This behavioral intervention was well-accepted and attenuated GWG among normal weight and class 1 obese women, compared to matched participants. Nevertheless, a more intensive intervention may be necessary to help women achieve GWG within the Institute of Medicine's guidelines.