Little is known about the contribution of attachment insecurity to Obsessive-Compulsive Disorder (OCD), though speculations have been extensive. We aimed to study how states of mind (SoM) with regard to attachment relate to OCD with and without depressive disorder (DD). We interviewed 100 adolescents, 25 each with OCD, DD, OCD plus DD and general population controls, using the Adult Attachment Interview (AAI) to assess attachment SoM. In the AAI, interviewees are asked about both generalized/semantic and biographical/episodic descriptions of childhood experience. Discourse styles are coded and classified by a blinded coder. While about half of the adolescents from the general population had secure SoM (52%), most adolescents in the clinical groups did not: OCD 12%; DD 8%; and DD + OCD 4% (Fisher's exact test, p = 0.0001). SoM with regard to attachment profiles differed significantly across the groups with 60% of participants with OCD classified as dismissing (Ds), 40% of the DD group as unresolved with regard to loss or abuse (U) and 28% as cannot classify, while 44 and 36%, respectively, of those with OCD + DD group were classified as either Ds or U (Fisher's exact test, p = 0.0001). Different kinds of SoM reflecting insecure attachment differentiated the clinical groups studied, with OCD predominantly showing dismissing traits and depression attachment SoM commonly associated with severe adverse events. Such differences might play distinct roles in the pathogenic processes of the psychiatric disorders, or be the result of the cognitive states associated with OCD and DD.