Carl Rogers was an influential American psychologist and was one of the founders of the Humanistic approach to psychology. In 1951 he published a book called Client-Centered Therapy (Rogers, Carl (1951). Client-centered therapy: Its current practice… London: Constable. ISBN 1-84119-840-4) and it revolves around the uses of counseling and therapy that can be effective in various setting including recovery from drug addiction treatment.
He proposed there are three necessary and sufficient conditions for personal change. These are unconditional positive regard, accurate empathy, and genuineness. He regarded negativity to be detrimental to helping a person change. Rogers believed the presence of these three items in the therapeutic relationship could help an individual overcome any troublesome issue, including alcohol or drug abuse.
To this end, a 1957 study (Ends, E.J., & Page, C.W. (1957). Quarterly Journal of Studies on Alcohol, 18, 263-277) compared the relative effectiveness of three different psychotherapies in treating alcoholics who had been committed to a state hospital for sixty days: a therapy based on two-factor learning theory, client-centered therapy and psychoanalytic therapy. Surprisingly, client-centered therapy proved most effective.
Many drug rehab and alcohol rehab centers now focus on the principals developed by Carl Rogers, most commonly the positive approach to personal change.