The purpose was to compare maternal perceptions, feeding practices, and overweight status of children in immigrant households in California (US) with a cohort in Guanajuato, Mexico (MX). In 2006, staff interviewed mothers and weighed and measured their children, 1-6 years (US: n = 95 and MX: n = 200). Prevalence of overweight [body mass index z-score (BMIZ) >1.0 and <1.65] and obesity (BMIZ > 1.65) was 21.1 and 28.4% in the US respectively, compared to 11.5 and 12.9% in MX (p < 0.001). No differences were observed in maternal ability to identify correctly the child's weight status or ever being told the child was overweight. US children ate away from home more often (p < 0.0001), had fewer family meals (p < 0.0001), and played outdoors less often than MX children (p < 0.0002). Further analyses should examine how differences in eating and activity patterns explain the disparity in childhood obesity across the countries.