Recent estimates indicate that illicit drug use in the United States remains a major problem. In 1996, an estimated 13 million people were current drug users—that is, they had used illicit drugs in the past month—which was down from a peak of 25 million in 1979. The number of current illicit drug users has remained relatively static since 1992. Marijuana is the most commonly used illicit drug, with about 10.1 million users in 1996. About half (54 percent) of the 1996 illicit drug users used marijuana only, while another 23 percent used marijuana and one or more other drugs. The remaining 23 percent of illicit drug users used only a drug other than marijuana. The number of current cocaine users declined from 5.7 million people in 1985 to 1.75 million in 1996. The estimated number of crack cocaine users in 1996 was about 668,000 and has remained steady at about this level since 1988. However, the use of heroin has been increasing recently, rising from 68,000 current users in 1993 to 216,000 current users in 1996. Among 12- to 17-year-old adolescents, current drug use rose from 5.3 percent in 1992 to 10.9 percent in 1995 but declined in 1996 to 9.0 percent. This decline is attributable to reductions in use among youth aged 12 to 15; for those aged 16 and 17, there was no change in current use from 1995 to 1996. The rate of marijuana use among adolescents more than doubled from 1992 to 1995. By 1996, 7.1 percent of adolescents had used marijuana in the past month. The same year, 0.6 percent of adolescents were current cocaine users, and 0.2 percent were current heroin users. Previous month use of hallucinogens nearly doubled from 1994 to 1996, from 1.1 percent to 2 percent. As part of its overall drug control effort, the federal government provides significant support for activities related to drug abuse treatment, including grants to states, direct services, and research. Fiscal year 1998 federal funding for treatment of drug abuse is approximately $3.2 billion, or about one-fifth of the total drug control budget. The Congress has authorized HHS and VA to spend the vast majority of federal drug abuse treatment funds. Federal spending on drug control recognizes four general areas of emphasis: demand reduction (which includes prevention, treatment, and related research), domestic law enforcement, interdiction, and international cooperation. For fiscal year 1998, the federal government budgeted a total of about $16 billion for drug control activities. The largest share of this budget—53 percent—supported domestic law enforcement activities. Drug abuse treatment accounted for 20 percent and prevention, for 14 percent; the remainder was allocated to interdiction and international efforts. (See fig. 1.) The proportion of drug control spending to reduce the demand for drugs has remained fairly constant since the mid-1980s at about one-third of the total. Since the early 1990s, federal spending for drug control has grown steadily. Total federal drug control funding rose by 64 percent, from about $9.8 billion in 1990 to about $16 billion in 1998. (See fig. 2.) During this period, the drug treatment budget increased slightly faster, 78 percent, growing from about $1.8 billion in fiscal year 1990 to $3.2 billion in fiscal year 1998. An additional $237 million above the 1998 level was requested for fiscal year 1999 treatment funding. Although a number of federal entities—including the Department of Justice, the Department of Education, and the Judiciary—receive treatment-related funding, HHS and VA receive the bulk of federal drug abuse treatment dollars (see table 1). For fiscal year 1998, HHS has been authorized to spend about $1.7 billion on drug abuse treatment—54 percent of all federal treatment dollars. For the same year, VA has received about $1.1 billion for drug abuse treatment and related costs, which is 34 percent of the federal treatment budget. Of the total growth in federal expenditures for drug abuse treatment between 1994 and 1998—about $557 million—increased funding to VA accounted for about 44 percent and to HHS, 33 percent. Of HHS’ $1.7 billion drug treatment budget for 1998, more than half ($944 million) was dedicated to the Substance Abuse and Mental Health Services Administration (SAMHSA) to support the treatment components of its Substance Abuse Performance Partnership Grants to states and the Knowledge Development and Application Program. Approximately 80 percent of SAMHSA’s total budget is distributed to the states through block grants and formula programs. SAMHSA has requested an increase of $143 million in fiscal year 1999 Substance Abuse Performance Partnership Grants funding to make treatment available to more of those who need it. The Health Care Financing Administration received $360 million in fiscal year 1998 to pay for drug abuse treatment services for Medicaid and Medicare beneficiaries. Eighty percent of this amount finances Medicaid treatment expenses, including all covered hospital and nonhospital services required. The remaining 20 percent covers Medicare hospital insurance treatment costs. The National Institutes of Health (NIH) received about one-sixth of HHS’s drug treatment funds to conduct research in the areas of drug abuse and underage alcohol use. For 1999, NIH has requested funding ($51 million) for its Drug and Underage Alcohol Research initiative to expand research on underage alcohol and drug addiction among children and adolescents, as well as chronic drug users, and to support increased dissemination of research findings. Recognizing the need to improve research on the infrastructure that delivers treatment, the Congress mandated in 1992 that the National Institute on Drug Abuse (NIDA) obligate at least 15 percent of its funding to support research on the impact of the organization, financing, and management of health services on issues such as access and quality of services. In 1998, VA was appropriated about $1.1 billion for inpatient and outpatient medical care provided to veterans with a diagnosis of drug abuse, as well as for drug abuse treatment services. Special substance abuse treatment services are available at 126 medical facilities. Additional monies support treatment research in coordination with NIDA. Other federal agencies that received drug treatment funds for fiscal year 1998 include the Departments of Education and Justice (each received more than $100 million), the federal Judiciary (about $75 million), and ONDCP (about $24 million). From 1994 to 1998, Justice’s funding rose 163 percent; moreover, its 1999 funding request would increase its funding by another third. The Department of Justice has requested about $83 million for fiscal year 1999 to support its Drug Intervention Program, a new program that would support drug testing, treatment, and graduated sanctions for drug offenders, in an effort to break the cycle of drug abuse and violence. The Government Performance and Results Act was enacted in 1993 in part as a means to improve performance measurement by federal agencies. It requires agencies to set goals, measure performance, and report on their accomplishments and thus should provide a useful framework for assessing the effectiveness of federally funded drug treatment efforts. However, demonstrating the efficient and effective use of federal drug abuse treatment funds is particularly challenging because most of these funds support services provided by state and local grantees, which are given broad discretion in how best to use them. Regardless, federal agencies are now required by the Results Act to hold states accountable for achieving federal goals for effective treatment outcomes. Drug addiction is a complicated disorder that includes physiological, behavioral, and psychological aspects. For example, the environmental cues that have been associated with drug use can trigger craving and precipitate relapse, even after long periods of abstinence. Despite the potential for relapse to drug use, not all drug users require treatment services to discontinue use. For those who do require treatment, services may be provided in either outpatient or inpatient settings, and via two major approaches: pharmacotherapy and behavioral therapy, with many programs combining elements of both. Other treatment approaches, such as faith-based strategies, have yet to be rigorously examined by the research community. In general, drug abuse is defined by the level and pattern of drug consumption and the severity and persistence of resulting functional problems. A diagnosis of drug abuse is generally made when drug use has led to social, legal, or interpersonal problems. A clinical diagnosis of drug dependence—or addiction—is based on a group of criteria including physiological, behavioral, and cognitive factors. In particular, drug addiction is characterized by compulsive drug-seeking behavior. People who are dependent on drugs often use multiple drugs and usually have substantial impairment of health and social functioning. Furthermore, addiction is generally accompanied by withdrawal symptoms and drug tolerance, resulting in the need to increase the amount of drugs consumed. Moreover, severe dependence is often associated with health conditions or impairments in social functioning, including mental health disorders that generally are serious and difficult to treat. Drug abusers are more likely than nonabusers to sustain injuries; be involved in violence and illegal activities; have chronic health problems, including a higher risk of contracting HIV (human immunodeficiency virus); and have difficulty holding a job. Most scientists agree that addiction is the result of chemical and physical changes in the brain caused by drug use. However, they recognize that addiction extends beyond physiological components to include significant behavioral and psychological aspects. For example, specific environmental cues that a drug abuser associates with drug use can trigger craving and precipitate relapse, even after long periods of abstinence. Therefore, people receiving treatment for drug abuse often enter treatment a number of times—sometimes in different approaches or settings, and sometimes in the same approach or even the same treatment facility. Often, the substance abuser reduces his or her drug use incrementally with each treatment episode. Experts recognize that not all drug users require treatment to forgo drug use because some drug users do not progress to abuse or dependence. Even among those who progress to the stage of abuse, some can stop drug use without treatment. This issue was addressed in a study of Vietnam veterans’ rapid recovery from heroin addiction.