The aim of this study was to examine and describe the effect of gender and socioeconomic status (SES) on preschool-aged children's overall development. Two hundred fifty-five preschoolers (125 boys and 130 girls), with a mean age of 56 plus or minus 9 months, were randomly selected from day care centers and kindergartens of different areas of Northern Greece. In terms of SES, the sample was divided to 3 groups (75 children coming from high-SES, 110 mid-SES, and 70 low-SES families) according to parental education, occupational status, and family income, which have been suggested as stable measures of SES. The overall development of children was assessed using the 6 scales of the Griffiths Test No. II. Two-way analysis of variance designs demonstrated no significant Group x Gender interaction ("p" greater than 0.05), whereas a post hoc analysis revealed that children coming from high-SES families had better scores on all domains of development examined than children of the other 2 SES groups ("p" less than 0.001). With respect to gender differences, no significant main effect on the General Developmental Quotient and on the Performance subscale ("p" greater than 0.05) was noticed, whereas there was a significant main effect noted in the remaining 5 scales. The findings of this study suggest that the related factors of SES and gender should be considered in the interpretation of Griffiths scales' performance, because they could prove to be important aspects that affect young children's general functioning.