On the basis of a survey of 1,088 households, it was estimated that there were about 23,000 bus and bus-related crimes in the survey area in 1983. This is 25 to 30 times the number reported by the Southern California Rapid Transit District for its entire service area. Comparisons with the 1980 census were made to evaluate the bias in the sample, and it was found that the sample probably underestimated the total amount of bus crime in the survey area. Bus and bus-related crime accounted for 20 to 30 percent of all crimes experienced by the central city population. Major sources of information loss are crimes occurring outside buses, but during a trip; nonreporting by victims; and statistical loss occurring because police do not categorize crime by transit use. More accurate and systematic data collection is recommended. 7 tables and 19 references. (Author abstract modified)