According to the University of Michigan's annual "Monitoring the Future" studies, from 1988-1999 the percentage of seniors who reported using Ritalin without a prescription went from 0.3 percent to 2.4 percent. In fact, in its 1994 report, data indicated that at that time, there were more U.S. high-school seniors who abused Ritalin than there were seniors who were legally prescribed the drug.[1]

According to a 1996 Drug Enforcement Agency (DEA) study of three states (Wisconsin, South Carolina, and Indiana), roughly 30-50 percent of adolescents in drug treatment centers reported "non-medical" use of methylphenidate. However, it wasn't identified as their primary drug of abuse.

A 1998 Indiana University study of 44,232 students found that 6.8 percent of ninth-graders surveyed reported using Ritalin illicitly at least once.

The Drug Enforcement Agency's "Drugs of Concern" Bulletin lists Ritalin alongside cocaine, LSD and ecstasy. Testifying before the House Subcommittee in May 2000, DEA Deputy Director Terrance Woodworth said that the extent to which adolescents are abusing methylphenidate is unknown, but that anecdotal evidence suggests that its incidence seems to have increased with the availability of the drug. In his statement to the committee, Woodworth said that "continued increases in the medical prescription of these drugs without the appropriate safeguards ... can only lead to increased stimulant abuse among U.S. children."

The Drug Abuse Warning Network's 1999 report on drug-abuse related visits to hospital emergency departments, shows 1,478 mentions for methylphenidate abuse, down from 1,728 in 1998. (In contrast, there were 168,763 cocaine-related visits to hospital emergency rooms.)

		DEA Press Release on Methylphenidate (October 1995)
		National Institute on Drug Abuse Fact Sheet on Ritalin
		Indiana Prevention Resource Center "FactLine" on the Non-Medical Use of Ritalin
		"Schoolyard Hustlers' New Drug: Ritalin" from the Christian Science Monitor
		"The Ritalin Racket" from Student.com

[1] The interpretation of the "Monitoring the Future" data appeared in an October 1995 press release from the Drug Enforcement Agency.