BACKGROUND Factors influencing excessive weight gain in pregnancy have not been well-studied among urban, low-income women. METHODS This prospective cohort study of 94 prenatal care patients at a large university hospital in Philadelphia examined associations of modifiable midpregnancy behaviors and nonmodifiable or early pregnancy factors with excessive gestational weight gain. Data were collected through questionnaires and medical record abstraction from 2009 to 2011. RESULTS The majority of women were African American (83%) and all (100%) received Medicaid. Nearly two thirds (60%) were overweight or obese in early pregnancy and 41% experienced excessive gain. In multivariable logistic regression analyses, significant predictors of excessive gestational weight gain included high early pregnancy body mass index (odds ratio [OR], 4.20; 95% confidence interval [CI], 1.43-12.34 for overweight/obese vs. normal weight), nulliparity (OR, 3.35; 95% CI, 1.17-9.62 for nulliparity vs. multiparity), and clinician advice discordant with Institute of Medicine guidelines (OR, 5.88; 95% CI, 1.04-33.32 for discordant vs. concordant advice). Watching under 2 hours of television daily (OR, 0.18; 95% CI, 0.03-1.03), and engaging in regular physical activity during pregnancy (OR, 0.35; 95% CI, 0.11-1.09) were suggestive of a reduced risk of excessive gain. CONCLUSIONS In this sample of urban, low-income women, high early pregnancy body mass index, nulliparity, and discordant clinician advice were directly associated with excessive gestational weight gain, with a trend toward decreased risk for viewing fewer hours of television and engaging in regular physical activity. Intervening on these targets may optimize gestational weight gain and promote long-term maternal health.