Few studies have examined the phenomenology of obsessive–compulsive disorder (OCD) in younger children. A sample of 292 treatment seeking youth with a primary diagnosis of OCD was divided into the young child (3–9 years old) and older child (10–18 years old) groups. Overall OCD severity did not differ between groups. However, older youth demonstrated stronger intensity of obsessive and compulsive symptoms, while younger children were rated as having less resistance and control of compulsions. Older youth exhibited increased occurrence of comorbid depression, and an increased occurrence of sexual, magical thinking, and somatic obsessions, as well as, checking, counting and magical thinking compulsions. Conversely, the group of younger children exhibited significantly poorer insight, increased incidence of hoarding compulsions, higher rates of comorbid attention deficit/hyperactivity disorder, disruptive behavior, and parent-rated anxiety, and more frequently exhibited hoarding compulsions. These differences suggest domains to consider when screening for OCD among younger/older pediatric cohorts.