His mother, Daphne, owned and taught at a private preschool and kindergarten for 25 years, later becoming a published poet and author of children's books.

Reynolds attended New Hanover High School, graduating in 1969, and turned down a Presidential appointment to the United States Naval Academy by Richard Nixon, after being drafted by the New York Mets.

He completed his internship at the Medical College of Georgia, being mentored there by Lawrence Hartlage as his interests turned more staunchly to neuropsychology.

He maintained a clinical practice for more than 25 years, primarily treating children who had been sexually assaulted as well as individuals with traumatic brain injury.

In 1987, the American Library Association declared his Encyclopedia of Special Education to be one of the top 25 reference works published in all fields that year.

He received the 50th Anniversary Razor Walker Award from the University of North Carolina at Wilmington for his service to the youth of America.

In 2002 he served as a distinguished visiting professor at Wilford Hall, the USAF showcase hospital and training facility at Lackland AF Base in San Antonio, Texas, where he also conducted grand rounds.

In 2017 he received the American Psychological Association's Nadine Murphy Lambert Award, which is given sparingly every 2–4 years to individuals based upon the unusual breadth and depth of their contributions to the field.

His early work, principally in the 1980s, on empirical evaluation of the cultural test bias hypothesis in clinical assessment was not only prolific but at the cutting edge of psychological science at the time and led to resolution of many of the polemic debates over the use of clinical assessment devices with native born American ethnic minorities and moved the remaining arguments from emotion to reasoned scientific dialogue (see for example his 1983, Journal of Special Education paper, “Test bias: In God we trust, all others must have data”).

At the same time, he was establishing important research programs in the areas of assessment of anxiety in children and youth and tackling the measurement issues surrounding the field of learning disabilities.

He is currently the author of 37 commercially published psychological tests, several of which have profoundly altered the practice of clinical assessment of child and adolescent behavioral and emotional disorders, but also have provided researchers in the field with much needed objective measures of behavior to the improvement of research in childhood psychopathology generally.

In 1994, he was one of 52 signatories on Mainstream Science on Intelligence,[2] an editorial written by Linda Gottfredson and published in The Wall Street Journal, which presented a scientific consensus regarding (then) current findings on intelligence to assist in clarifying and differentiating mainstream consensus findings on the issue from some of the more scientifically controversial statements in Herrnstein and Murray's volume, The Bell Curve (in which he was miscited as "Cyril" Reynolds).