This paper reports results of intensive field work in urban high school mathematics and science classrooms based on research with students attending eight high schools located in large, disparate urban sites across the U.S. During the course of our observations and interviews we recorded students' activities as well as their impressions of classroom processes over the course of a week in each classroom using the Experience Sampling Method (ESM). ESM allows students to record information about their classroom experiences at intervals during daily mathematics and science classroom lessons. We measured levels of student engagement and examined relationships between student engagement and an array of predictors. We take a social organizational approach to interpreting classroom processes, examining the extent to which classroom activities influence student perception of class and communication among students and how these intervening factors affect student engagement during on-going classroom activities. Results suggest that there is variation between group members' reactions to classroom activities. Specifically, as an example, Latino Students in Chicago, Miami and El Paso were far more engaged and responsive to classroom lessons during the time they spent in small problem-solving groups during class. Student Engagement in High School Mathematics and Science.