This study investigated whether Foygel and Dell's (2000) interactive two-step model of speech production could simulate the number and type of errors made in picture-naming by 68 children of elementary-school age. Results showed that the model provided a satisfactory simulation of the mean error profile of children aged five, six, seven, eight and eleven years-old. Consistent with previous research, children made a relatively large number of semantic errors when naming pictures. This was particularly noticeable for several of the younger children who made more semantic errors than the model would predict. This discrepancy between the data and the model seemed to occur because some semantic errors made by the younger children reflected a lack of semantic knowledge about the target word rather than retrieval failures. When the simulation was confined to 25 highly familiar picture names, the Foygel and Dell (2000) model provided a good fit to the observed data from children of all ages. Our findings suggest that the differences between the speech production systems used by children and adults are quantitative rather than qualitative. Connections between semantic and lexical representations and between lexical and phonological representations appear to increase in strength linearly as children get older. (Contains 4 tables and 2 figures.)