This paper explores the historical origins of attention deficit disorder/attention deficit hyperactivity disorder (ADD/ADHD) as a neurological disorder, current neurological and genetic research concerning the etiology of ADD/ADHD, and implications for diagnosis and treatment. First, ADD/ADHD is defined and then the origins of ADD/ADHD as a neurological disorder are traced in a review of the periods of 1800 to 1950, 1950 to 1970, 1970 to 1990, and 1990 to 1999. The review then goes on to consider implications of neuro-imaging technology, a look at frontal lobe and parietal lobe involvement, and implications of the neuro-transmitter dysfunction theory. Examination of ADD/ADHD and genetics reviews family studies, twin studies as a basis for ADHD genetic etiology, and adoption studies. Discussion of other genetic discoveries notes new research concerning the thyroid hormone receptor and a dopamine transporter gene. The final section considers assessment and treatment of ADD/ADHD including current assessment procedures, traditional treatment, and other treatment approaches. One of the five conclusions is that neurological studies involving brain scans indicate brain peculiarities in approximately 70 percent of the children diagnosed with ADD/ADHD. (Contains 39 references.) (DB)