The aim of this study was to assess the somatic development of children from an urban agglomeration in Poland at the end of preschool education and the beginning of primary education with respect to selected socioeconomic and educational conditions. Data were collected for 742 children from selected Warsaw kindergartens in spring 2011 and 2012. Their mean age was 5.84±0.31 years. The sex categories were equal: 371 boys and 371 girls. Kindergartens chosen for the study constituted a representative sample. The diagnostic survey method (questionnaire technique) was used to assess the selected environmental conditions of development in the participating children. Body height and the sum of six skin folds (over the biceps, over the triceps, under the scapula, on the abdomen, over the wing of ilium and on the calf) were chosen from the assessed anthropometric parameters for the purpose of determining somatic development of study participants. The obtained data were analysed using selected descriptive statistics methods (including cluster analysis), data standardization (normalization by mean values and SD) and the chi-squared test. The results showed certain relationships between the selected parameters of somatic development and family living conditions. These relationships involved differences between individual clusters depending on given living conditions and were most prominent for mother's education, for which variable differences between clusters were found for both sexes. The somatic build of boys (including body height and body adiposity) also differed depending on the number of offspring in the family, while the somatic build of girls differed depending on father's employment and father's education. Furthermore, the obtained results lead to the conclusion that the total number of differences between the analysed clusters was relatively low. This indicates that the biological effects of social stratification tend to diminish in the environment of an urban agglomeration.