An explanation of the Uniform Crime Reports system in Maryland is followed by definitions of Part I and Part II index offenses. Data then show the volume of index offenses by month for 1990. Volume by month is also shown for violent crime, property crime, murder, rape, robbery, aggravated assault, breaking or entering, larceny, motor vehicle theft, and arson. For stolen property there is an analysis of value stolen and recovered, and data on murder cover distribution by circumstances and by weapon type. Distribution by offense classification is shown for robbery, breaking or entering, and larceny. Data on arson encompass distribution by type of property. Index offense data are also reported by region, county, municipality, and agency. Arrest data cover juveniles; adults; the arrest rate over 5 years; and the age, race, and sex of persons arrested. Arrests are presented by region, county, and agency. Data on police assaults address circumstance, time of day, and agency. Data on sworn law enforcement employees show a 10-year county trend. A supplement presents arrest data for each of the index offenses.