Patterns and correlates of comorbidity, as well as differences in manifest depressive profiles were investigated in a sample of depressed adolescents. A sub-sample of the youth were characterized as belonging to either a "Pure" depression group, an "Internalizing" group (depression and co-occurring internalizing disorders), or an "Externalizing" group (depression and co-occurring externalizing disorders). Item response theory (IRT) and differential item functioning (DIF) were used to assess whether the depressed adolescents from the different comorbidity groups presented with different depressive symptoms. Results indicated that the comorbidity groups were meaningfully distinct in terms of psychosocial correlates as well as showed differences in depressive symptom profiles as informed by DIF analyses. In particular, the comorbidity groups differed in terms of presentation of psychomotor changes and cognitive impairments. Implications for assessment are discussed.