Criterion validity and test-retest reliability of the Scale of Psychomotor Development (SPMD) was studied on groups of children of 4–6 years old. A conclusion about developmental delay or delayed speech development was used as a criterion of external validity. To examine the accuracy of the differential diagnostics of the three groups (the norm and two groups with the above diagnoses) a discriminant analysis was used. The results showed high accuracy in predicting the subject's belonging to the norm group or developmental delay group, and lower prediction accuracy for the group with delayed speech development in differentiation with the norm and developmental delay.