A cross-sectional survey design was adopted to validate the Frequency of Delinquent Behavior Scaling Instrument (FDBSI) using adolescents from a secondary school in Lagos, Nigeria. A combined purposive and convenient sampling technique was used to select 261 participants made up of 93 males (35.6%) and 168 females (64.4%) from a selected secondary school in Kosofe Local Government in Lagos State Nigeria. The mean age was 15.57 ± 1.97. Participants responded to Frequency of Delinquent Behavior Scaling Instrument (FDBSI) and Self-Reported Delinquency (SRD) to determine concurrent validity. Observed internal consistency of FDBSI showed a Cronbach's alpha coefficient of .75, a Spearman-Brown coefficient of .68 and Guttman Split-Half coefficient of .68. All items in the scale reported acceptable goodness-of-fit measures revealing corrected item-total correlations range of .12 to .79. Significant positive correlation was also observed between FDBSI and SRD revealing concurrent validity score of (r = .292, p= .000). Determined new norms for FDBSI were scores of 28.4 for male, and18.8 for female. FDBSI is observed to be gender sensitive and has acceptable psychometric properties for Nigerian adolescent population.
