To study the in class learning experiences of mainstreamed handicapped students, academic learning time (ALT) was measured for 79 mainstreamed learning disabled (LD) and 143 regular fifth and sixth graders in year 1 and 62 mainstreamed LD students and 166 regular students in year 2. Analyses of student records, responses to teacher questionnaires, and classroom observation revealed significant differences between LD and regular Ss in all five year 1 ALT variables: allocated time, engaged time, time on high success tasks, time on medium success tasks, and time on low success tasks. When ALT is defined as percent of time on high success tasks, mainstreamed students had less than half the ALT of their regular counterparts. Factors associated with ALT included sex (girls tended to have more engaged time and high success time, and less medium success time than boys) and age (younger mainstreamed girls had more ALT than older students in general). The relationships of teacher background variables to ALT variables was negligible. The teacher's instructional behavior was strongly correlated with student engagement. Overall, ALT measures were relatively unstable from 1 week's observation to the next, and from one study year's average to the next. (CL)