Section Editors Robert J. Yetman, MD Corresponding Editor University of Texas School of Medicine Houston, Texas Polly F. Cromwell, MSN, RN, CPNP Pediatric Primary Care Center Bridgeport Hospital Bridgeport, Connecticut This article is the second section of a three-part clinical guideline on attention deficit hyperactivity disorder (ADHD). Part II provides concrete approaches to the assessment of this complex and heterogeneous disorder, while Part III will address its management, including behavioral, educational, and pharmacologic interventions. In 2000 the American Academy of Pediatrics (AAP) developed clinical practice guidelines for the assessment and management of ADHD in the primary care setting. These guidelines will be incorporated into the following discussion of ADHD because they continue to provide the standard of care for persons with this disorder. Robert J. Yetman, MD Corresponding Editor University of Texas School of Medicine Houston, Texas Polly F. Cromwell, MSN, RN, CPNP Pediatric Primary Care Center Bridgeport Hospital Bridgeport, Connecticut Patricia Ryan-Krause, Associate Professor, Pediatric Nurse Practitioner Specialty, Yale University School of Nursing, New Haven, CT.