In 1980, 16 homicides, 69 rapes, 294 robberies, 643 assaults, 1,552 burglaries, 6,230 larcenies, and 250 vehicle thefts were reported in national parks. All offenses were record numbers in a year when a record 300 million visitors entered the 334 jurisdictions operated by the National Park Service. The Park Service has two law enforcement arms--the park police and enforcement rangers. Park police (1,100 officers) enforce the law in the urban parks of the Washington, D.C., area and two other urban national parks in New York and San Francisco. The park police also have 10 captains stationed in national parks around the country; they provide technical assistance to park rangers working in law enforcement. 'Enforcement rangers' stationed in national parks are rangers who specialize in law enforcement. Enforcement rangers do not have the extensive law enforcement training of the park police. Yosemite National Park, located only a few hours' drive from Los Angeles and San Francisco, is one of the most crime-plagued areas operated by the Park Service. One of every nine Part 1 crimes reported in the Park Service system in 1980 occurred in Yosemite. Many in the Park Service fear that the trend in Yosemite may spread to other parks, as those affected by the struggling economy seek cheaper forms of recreation. A more serious approach to policing in the parks may be required in the future. Photographs are included.