The length of time needed for professional therapy varies depending on the severity of your child's OCD and his response to treatment. An initial course of CBT for OCD will usually last a minimum of twelve weeks of forty-five-minute sessions and may require up to twenty weeks.

If your child takes quickly to the ERP process and is diligent at recording his progress and monitoring his own behaviors, he may not require additional one-on-one therapy after twelve sessions. After an initial period of regular therapy, your child's therapist should remain available to you for regular (typically every three to four months) follow-up sessions, or for an “emergency” session in the event of a major slip or if a new obstacle comes up in your child's independent progress.

This is an area where the perfectionism of OCD can be turned to good purposes. That is, if it doesn't go too far. A sure way to sabotage progress in treating OCD is by having an all-or-nothing attitude. Conversely, one of the sure signs of success is when a perfectionist decides something is “good enough for now.” And then there's the strong likelihood, make that a certainty, that he'll have slips and regressions in his progress along the way.