A study of 39 elementary schools in Chicago was conducted to compare two sets of schools, those whose students made above average yearly gains in reading comprehension and those whose students' reading gains were below average. These schools were compared on the proportion of time spent on task, on what the teacher and pupils did during reading instruction, and the rated qualities of the teachers and pupils on subjective measures. The sets of schools did not differ on class size, staffing costs, number of non-English speaking students, experience or education level of teachers, percent of minority pupils, retention rate, reading appropriations, assaults, vandalism, security costs, or suspensions. The proportion of time that reading was the teacher's main task differed significantly and the teachers in high gain schools were rated by observers to have better organized lessons and to be better managers of time. (The classroom observation form used in the study is included.) (TJ)