Growing evidence links perceived stress-a potentially modifiable psychosocial risk factor-with health behaviors and obesity. Yet little is known about the relationship between stress during pregnancy and gestational weight gain, particularly among women with pregnancy complications. We conducted a cross-sectional analysis to examine associations between psychosocial stress during pregnancy and gestational weight gain among women with gestational diabetes. We used baseline data from the Gestational Diabetes’s Effects on Moms (GEM) study: 1,353 women with gestational diabetes who delivered a term singleton within Kaiser Permanente Northern California were included. Perceived stress near the time of gestational diabetes diagnosis was measured using the validated Perceived Stress Scale (PSS10). Gestational weight gain was categorized according to the 2009 Institute of Medicine recommendations. Binomial regression analyses adjusted for gestational age and maternal age at the time of gestational diabetes diagnosis, and race/ethnicity and estimated rate ratios (RR) and their 95% confidence interval (CI). Among women with a normal pregravid Body Mass Index (BMI 18.5-24.9 kg/m2), there was a significant association between high (Q4) PSS score and risk of both exceeding and gaining below the Institute of Medicine recommendations compared to those with lower stress (Q1) [adjusted RR = 2.16 95% CI 1.45-3.21; RR = 1.39 95% CI 1.01-1.91, respectively.] Among women with pregravid overweight/obesity (BMI≥25 kg/m2), there was no association. Although the temporal relationship could not be established from this study, there may be a complex interplay between psychosocial stress and gestational weight gain among women with gestational diabetes. Further studies examining stress earlier in pregnancy, risk of developing gestational diabetes and excess/inadequate gestational weight gain are warranted to clarify these complex relationships.