UNLABELLED: Studies conducted among nonpregnant populations have observed an association between sedentary behavior and glucose intolerance. Few studies have investigated this association during pregnancy, particularly among Latina women, a population with higher rates of sedentary behavior and abnormal glucose tolerance (AGT) as compared with non-Latina white women. OBJECTIVE: The purpose of this study was to estimate the association between sedentary behavior and AGT. RESEARCH DESIGN AND METHODS: We used data from the Latina gestational diabetes mellitus study, a prospective cohort of 1231 Latina prenatal care patients in western Massachusetts. Sedentary behavior was assessed by bilingual interviewers using a modified version of the Kaiser Physical Activity Survey in prepregnancy, early pregnancy, and midpregnancy and defined as hours spent TV watching, frequency of sitting at work, and participation in sports or exercise activity as well as a derived composite of total sedentary activity. AGT was measured at 24-28 wk of gestation and abstracted from medical records after delivery. Multivariate logistic regression was used to calculate odds ratios and 95% confidence intervals. RESULTS: A total of 12% (n = 119) of participants were classified as having AGT. After adjusting for AGT risk factors, sedentary behaviors in prepregnancy or in early pregnancy were not associated with AGT. However, in midpregnancy, low levels of participation in sports or exercise (odds ratio = 2.01, 95% CI = 1.01-4.02) and increasing total sedentary activity (Ptrend = 0.003) were associated with increased risk for AGT. CONCLUSIONS: Findings suggest an association between sedentary activity in midpregnancy and risk of AGT in this understudied population.