Purpose: To determine the effect of a Nutrition and Exercise Lifestyle Intervention Program (NELIP) for overweight (OW) and obese (OB) pregnant women on pregnancy weight gain, birth weight, and maternal weight retention at 2 months postpartum. Methods: This is a single-arm intervention matched by prepregnant body mass index, age, and parity to a historical cohort (4:1). Women with a prepregnancy body mass index of>25.0 kg•m (N = 65) participated in a NELIP starting at 16-20 wk of pregnancy, continuing until delivery. NELIP consisted of an individualized nutrition plan with total energy intake of approximately 2000 kcal•d (8360 kJ•d) and 40%-55% of total energy intake from carbohydrate. Exercise consisted of a walking program (30% HR reserve), three to four times per week, using a pedometer to count steps. Matched historical cohort (MC; N = 260) was from a large local perinatal database. Results: Weight gained by women on the NELIP was 6.8 ± 4.1 kg (0.38 ± 0.2 kg•wk), with a total pregnancy weight gain of 12.0 ± 5.7 kg. Excessive weight gain occurred before NELIP began at 16 wk of gestation. Eighty percent of the women did not exceed recommended pregnancy weight gain on NELIP. Weight retention at 2 months postpartum was 2.2 ± 5.6 kg with no difference between the OW and the OB women on NELIP. Mean birth weight was not different between NELIP (3.59 ± 0.5 kg) and MC (3.56 ± 0.6 kg, P > 0.05). Conclusions: NELIP reduces the risk of excessive pregnancy weight gain with minimal weight retention at 2 months postpartum in OW and OB women. This intervention may assist OW and OB women in successful weight control after childbirth. Copyright © 2010 by the American College of Sports Medicine.