The developmental status of 1,180 children representing a cross section of Denver's ethnic and parental occupational groups was compared with that of 1,055 children (349 Anglo, 354 Spanish surname, and 352 Black) whose parents were unskilled workers. The children varied in age from 2 weeks to 6.4 years and were evaluated with the Denver developmental screening test. Comparisons were made in developmental achievements as reflected by individual item differences for Anglo children from unskilled families with Anglos from cross-sectional families. A second comparison of Anglo, Spanish, and Black children of the unskilled sample was also made. The first analysis comparing 910 Anglo children from the cross-sectional sample with 349 Anglo children from the unskilled families demonstrated significant differences (p smaller than 0.05) for 39 of the 105 items. Below 20 months of age, children of the unskilled sample were more advanced, whereas after 20 months of age, the children of the cross-sectional sample were advanced in all test sectors except for items in the personal-social sector. Comparisons of Anglo, Black, and Spanish surname children from the unskilled families showed fewer differences in rates of development.