Background Child development is determined by both biological (e. g. gender, natal maturity) and psychosocial (e. g. socioeconomic status, daycare) factors. Objectives To examine how familial socioeconomic status (SES) as well as biological and other psychosocial factors are associated with the state of development of 4-and 6-year-old children. Methods Data linkage of primary data from a birth cohort study and routine data from the Saxon public health departments on children born between 2007 and 2008, who underwent both daycare health examination and school entry health examination (N=615), was used to examine speech and motor skills, both fine and gross, for associations with psychosocial and biological factors. Potential associations were tested for significance and shown as odds ratios by using binary logistic regression. Results There were no noticeable problems in the development of the majority of Saxon children until school entry. Nevertheless, language seems to be a sensitive area of development, since 37% of the children showed problems at both time-points. Furthermore boys, preterm infants and children from a lower socio-economic class were more often affected by developmental delays, with preterm infants with low SES being at very high risk. Furthermore, the point of time of entering daycare seems to be of relevance for child development. Conclusions The results are in line with national and international findings. An important new finding is the significantly increased likelihood of having developmental problems when biological and psychosocial risk factors coincide. However, longitudinal analyses are required to study developmental courses and to evaluate measures initiated to combat these issues.