Abstract Background At present, there is no evidence on whether using condition-specific Oral Health-Related Quality of Life (OHRQoL) measures provides more reliable information than generic measures for needs assessment. Therefore, the objective was to assess the discriminative ability of one generic and one condition-specific OHRQoL measure, namely, respectively, the short form of the Oral Health Impact Profile (OHIP-14) and the Condition-Specific form of the Oral Impacts on Daily Performances (CS-OIDP) attributed to malocclusion, between adolescents with and without normative need for orthodontic treatment. Methods 200 16–17-year-old adolescents were randomly selected from 957 schoolchildren attending a Sixth Form College in London, United Kingdom. The impact of their oral conditions on quality of life during the last 6 months was assessed using two OHRQoL measures; OHIP-14 and OIDP. Adolescents were also examined for normative orthodontic treatment need using the Index of Orthodontic Treatment Need (IOTN) and the Dental Aesthetic Index (DAI). Discriminative ability was assessed comparing the overall scores and prevalence of oral impacts, calculated using each OHRQoL measure, between adolescents with and without normative need. Using the prevalence of oral impacts allowed adjusting for covariates. Results There were significant differences in overall scores for CS-OIDP attributed to malocclusion between adolescents with and without normative need for orthodontic treatment when IOTN or DAI were used to define need (p = 0.029 or 0.011 respectively), and in overall scores for OHIP-14 when DAI, but not IOTN was used to define need (p = 0.029 and 0.080 respectively). For the prevalence of impacts, only the prevalence of CS-OIDP attributed to malocclusion differed significantly between adolescents with and without normative need, even after adjusting for covariates (p = 0.017 and 0.049 using IOTN and DAI to define need). Conclusion CS-OIDP attributed to malocclusion was better able than OHIP-14 to discriminate between adolescents with and without normative needs for orthodontic treatment.