The Certified Co-Occurring Disorders Professional (CCDP) and Certified Co-Occurring Disorders Professional Diplomate (CCDP-D) provides assessment and counseling to persons with co-occurring mental and substance use disorders, and when appropriate, family/significant others. CCDPs possess the knowledge and skills specific to both mental and substance use disorders, as well as to the interactions among the disorders. They assist persons with co-occurring disorders to engage in and maintain a process of recovery.