Decisions about scheduling classroom activities and routines are often based upon beliefs about when students are most able to learn. There is little research available to base these beliefs on. We investigated student academic responding time as a function of time of day for 122 students with and without disabilities in 10 schools in urban and suburban districts. We recorded student behavior in 19 domains and 12 instructional activities. Students were observed all day, and data were collected in 10-second intervals. Student academic responding time was higher when an academic activity was occurring, an active task was being used, and an individual rather than group structure was in place no matter what the time of day. This instructional arrangement occurred more often in the morning. We conclude that response time is a function of classroom ecology rather than time of day.