In 1975 Public Law 94-142 was enacted requiring public agencies to ensure that handicapped children were educated to the maximum extent possible with nonhandicapped children. This educational practice became known as "mainstreaming". The present study was conducted to determine the quantity of mainstreaming as indicated by analysis of handicapped students' schedules. The primary study purpose was to ascertain if the quantity of the instructional opportunity, i.e., allocated learning time, for mainstreamed students was equitable to nonhandicapped students' instructional opportunity for the same subject. The setting was a medium-sized rural, K-12 school district. The study sample included 336 handicapped students served in resource specialist and special day class programs. Students in the sample were identified as learning disabled, mildly mentally retarded, severely mentally retarded, severely emotionally disturbed, multiply handicapped, or severely language disabled. It was found that 72.6% of the students participated in mainstreamed classes. The most commonly utilized classes for mainstreaming purposes were physical education (63%), social studies (48%), art (43.5%), and science (42%). In six of the fourteen subjects in the study used for mainstreaming, the entire sample experienced equal instructional time as their nonhandicapped classmates. In the remaining eight subject areas, mainstreaming as a percentage of regular classroom instructional time allocated to that subject was very high, ranging from 85% to 99.2%. Thus, the results demonstrated a close relationship between the instructional opportunity afforded a mainstreamed handicapped student and a nonhandicapped student for a given subject area. In the nonacademic area, as expected, recess and lunch were most often mainstreamed. A significant difference was found between students with different handicapping conditions in the percent of the school day spent in mainstreamed settings. No difference was found between various school levels. Principals reported academic ability and socialization skills as the major factors affecting a handicapped student's success in a mainstreamed setting. They also reported teacher attitudes as a primary contributing factor to the success of mainstreaming. No hurdles or difficulties were reported to impede the opportunity for mainstreaming at their school. In conclusion, it was demonstrated that in a high percentage of cases, equity in allocated learning time existed for mainstreamed handicapped students.