This study examined racial/ethnic differences in gestational weight gain (GWG) predictors and association of first-trimester GWG to overall GWG among 271 White women and 300 Latina women. Rates of within-guideline GWG were higher among Latinas than among Whites (28.7% versus 24.4%, p < 0.016). Adjusted odds of above-guideline GWG were higher among prepregnancy overweight (OR = 3.4, CI = 1.8-6.5) and obese (OR = 4.5, CI = 2.3-9.0) women than among healthy weight women and among women with above-guideline first-trimester GWG than among those with within-guideline first-trimester GWG (OR = 4.9, CI = 2.8-8.8). GWG was positively associated with neonate birth size (p < 0.001). Interventions targeting prepregnancy overweight or obese women and those with excessive first-trimester GWG are needed.