After completing his undergraduate studies at San Diego State University, Rimland obtained his PhD in experimental psychology and research design, from Pennsylvania State University in 1953.

Dr. Rimland's son, Mark, was born in 1956, when the diagnosis of autism was rare. From birth, however, something was drastically wrong with Mark. Rimland had recently earned his doctorate, but was not yet familiar with the word autism. Only much later was it determined Mark's condition fell into the category of early infantile autism, rather than regressive autism. Despite challenges, Mark has nevertheless become a talented artist.

After his son's diagnosis, Rimland set forth on a quest to understand autism and bring much needed attention to the disorder, in order to foster research into its causes and treatment. Rimland has often sparked controversy along his way.

Rimland published his book, Infantile Autism: The Syndrome and Its Implications for a Neural Theory of Behavior, in 1964. Its foreword, by Leo Kanner, the man who first identified autism as a syndrome, gave the book credibility among professionals in the field. It was an about-turn for Kanner, the originator of the word "autism" and of the "refrigerator mother" theory; through his observations and research, Kanner had come to believe that autism had a neurological cause...the accepted view in the medical profession today. But at the time Rimland's book was published,and for many years afterwards, the standard theory was that autism was caused by unloving 'refrigerator mothers', an unproven but widely accepted idea most famously propounded by University of Chicago professor Bruno Bettelheim, notably in his book The Empty Fortress: Infantile Autism and the Birth of the Self (1967), which claimed that the traumatized unloved child retreated into autism. As a professional research psychologist, Rimland was well positioned to launch the first major attack on Bettelheim's theory. Rimland's was the first authoritative voice to dispute Bettelheim's research and call into question his conclusions.

Parents from all over the United States, excited that for the first time a professional in the field did not accuse them of maltreating their autistic child, began to write to Rimland. He called a meeting in Teaneck, New Jersey, at the house of one of the families, and this small group of parents, including among others Ruth C. Sullivan (first president of the ASA), became the nucleus that founded the Autism Society of America.

In 1967, Dr. Rimland established the Autism Research Institute (ARI) - the hub of a worldwide network of parents and professionals concerned with autism. ARI was founded to conduct and foster scientific research designed to improve the methods of diagnosing, treating, and preventing autism. ARI also disseminates research findings to parents and others worldwide seeking help via their * [1] website. The ARI data bank, the world's largest, contains over 40,000 detailed case histories of autistic children from over 60 countries.

Another one-of-a-kind database that Dr. Rimland started was the “Parent Ratings of Biomedical Interventions”. Since 1967, over 26,000 parents have completed surveys indicating the extent to which various treatments helped their children. This information is on ARI’s site to help both parents of autistic children and physicians decide on a possible course of treatment.

Many senior figures in medicine and psychology questioned Rimland's contributions to autism during the later period of his career. In 1995, Bennett Leventhal, a professor at the University of Chicago, tersely dismissed as "rubbish" Rimland's concern about the rise in autism diagnoses, and his assertion that vaccinations might be among the causes. Rimland was among a minority of researchers who believe that thiomersal (a mercury-based preservative) used in vaccines is a direct cause of autism. The United States Institute of Medicine (IOM) in its 2004 report found that, "the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism."[2] The Medicines and Healthcare products Regulatory Agency (MHRA), National Health Service (NHS), World Health Organization (WHO), European Medicines Agency (EMEA), Food and Drug Administration (FDA), Centers for Disease Control (CDC), and many other national and international medical organizations have issued statements of a similar nature, finding no link between autism and thimerosal based on the evidence currently available from a variety of studies.

In her book, Children with Starving Brains, Jaquelyn McCandless, MD, calls Rimland "The grand godfather of the movement for understanding the biological treatment of autism". Rimland's book, Infantile Autism: The Syndrome and Its Implication for a Neural Theory of Behavior (1964), is credited by many with changing the prevailing view of autism, in the field of psychiatry, from an emotional illness -widely thought to be caused by refrigerator mothers - to the current recognition that autism is a neurodevelopmental disorder.

Rimland was among the first autism campaigners to draw attention to increases in the number of diagnoses of autism. After correlating the presence of mercury in vaccines with the increase in autism cases, Dr. Rimland concluded that mercury is the primary culprit in the epidemic rise of autism: back in 1990, one out of ten thousand infants as compared to one out of one hundred and fifty at present (March 2007) representing an increase of 6,670%. To this day, the medical establishment still does not know the cause of autism.

Rimland has lectured on autism and related problems throughout the world, including before thousands of professional groups, and he is the author of numerous publications. His high profile, within what was then a small community of autism activists, caught the eye of movie producers in nearby Hollywood, California.

Rimland subsequently served as the primary technical advisor on autism for the 1988 movie Rain Man. Mark Rimland was interviewed by Dustin Hoffman, serving as one of several models for the character portrayed by the movie star. The movie helped establish worldwide awareness of autism, just when the prevalence of autism was first becoming apparent.

Dr. Rimland was the editor of the Autism Research Review International, published by ARI, which covers biomedical and educational advances in autism research.

Rimland and his wife, Gloria, had recently celebrated their 50th wedding anniversary. The couple was married by Rabbi Monroe Levens of Tifereth Israel Synagogue, which was then located in Kensington, California.