Some individuals with obsessive–compulsive disorder (OCD) have autistic-like traits, including deficits in social and communication behaviors (pragmatics). The objective of this study was to determine if pragmatic impairment aggregates in OCD families and discriminates a clinically and genetically distinct subtype of OCD. We conducted clinical examinations on, and collected DNA samples from, 706 individuals with OCD in 221 multiply affected OCD families. Using the Pragmatic Rating Scale (PRS), we compared the prevalence of pragmatic impairment in OCD-affected relatives of probands with and without pragmatic impairment. We also compared clinical features of OCD-affected individuals in families having at least one, versus no, individual with pragmatic impairment, and assessed for linkage to OCD in the two groups of families. The odds of pragmatic impairment were substantially greater in OCD-affected relatives of probands with pragmatic impairment. Individuals in high-PRS families had greater odds of separation anxiety disorder and social phobia, and a greater number of schizotypal personality traits. In high-PRS families, there was suggestive linkage to OCD on chromosome 12 at marker D12S1064 and on chromosome X at marker DXS7132 whereas, in low-PRS families, there was suggestive linkage to chromosome 3 at marker D3S2398. Pragmatic impairment aggregates in OCD families. Separation anxiety disorder, social phobia, and schizotypal personality traits are part of a clinical spectrum associated with pragmatic impairment in these families. Specific regions of chromosomes 12 and X are linked to OCD in high-PRS families. Thus, pragmatic impairment may distinguish a clinically and genetically homogeneous subtype of OCD. © 2014 Wiley Periodicals, Inc.