The study examined the validity of the Five to Fifteen (FTF) questionnaire in detecting developmental disorders in five-year-old children. A pilot study (N=70) was first undertaken to try out a translation of the FTF into Finnish. Subsequently, FTF questionnaires were mailed to parents of all five-year-old children from specified health-care districts in Vantaa, Finland. A total of 769 questionnaires (60%) were completed and returned. Children scoring above a cut-off value in any domain were considered at risk for having developmental disorders (the Risk Group; N=90). A Control Group was formed by randomly selecting 30 children who did not score above the threshold value in any domain. The children from the Risk Group and the Control Group were called to individual neuropsychological assessments. All invited children attended the assessments. The parts of the FTF that assess fine motor skills, executive functions (including attention and impulsivity), perception, memory, and language were used for this study. The external criterion measure was the NEPSY, a neuropsychological assessment instrument. Results demonstrated that the five FTF Domain Scores used in this study correlated significantly with the corresponding NEPSY Domain Scores. Second, the Risk Group obtained significantly poorer scores on the NEPSY than the Control Group. Third, on a cross-tabulation a very high rate of positive hits (93 %) was obtained as well as a very low rate of misses (7 %), indicating a very good sensitivity. However, there were a large percentage of false positives (63 %), indicating that specificity was not so good. Evidently, parents may report concerns related to the young child's development even when neuropsychological assessments do not indicate significant disorders. On the whole, the findings supported the validity of the FTF as a developmental screening instrument.