In June 1975, Maine became the third State to decriminalize the possession of marijuana. The law took effect on May 1, 1976, and since then persons who possess any amount of marijuana for their personal use in Maine are not subject to arrest and imprisonment. Instead, they are cited or ticketed for a civil violation punishable by a maximum $200 fine. Despite the passage of 4 years, decriminalization of marijuana continues to generate legislative and public debate. In response to this controversy, this analysis was conducted to determine possible time/cost benefits of the legislation. Data considered include the number of arrests or citations for the period 1975 through 1978, pretrial police time and money spent in making an arrest or issuing a citation, trial costs compared with costs for processing civil defendants, postconviction costs, and total costs of processing marijuana possession offenders under both penalties. With the exception of one border town, the number of citations issued in 1978 was 1 percent less than the number of arrests made in 1975. Using cost per hour figures computed from police budgets, making an arrest is 5 to 13 times more expensive than issuing a citation. Statewide, the decriminalization of marijuana has reduced the number of defendants who plead not guilty by 87 percent. This effect alone has saved thousands of hours of police, prosecutors' and judges' time and has produced an annual saving of $188,000. Moreover, decriminalization has caused a 99-percent reduction in the number of requests for marijuana possession pretrial suppression hearings. In 1975, 323 defendants charged with possession requested a trial in superior court. In 1978, the superior court heard two possession cases. In 1975, 39 persons convicted of possession were imprisoned in a county jail or State correctional center at a cost of $30,000. No offenders have been imprisoned since decriminalization. Under the present system of civil penalties, the State has made money because fines were $16,957 greater than the costs of arrest and prosecution. In addition, decriminalization has substantially improved the quality and uniformity of justice administered to such defendants in Maine. Footnotes and 11 tables are included. An appendix includes a formula, which is applicable to other States, for determining the dollar amount saved from decriminalization of marijuana possession.