An ethnographic study was conducted in an elementary school in order to understand the relationship between teacher behavior and the environments of classes identified by teachers as their "worst." First, research on teacher behaviors was reviewed to identify a set of factors identifiable with effective and ineffective teaching. Ten dimensions of teacher behavior were identified: maintaining time on task; feedback; grouping; praise; questioning and wait time; structuring; student choice; warmth; task-oriented, business-like behavior; and teacher expectancy. Eleven classes described by teachers as their "worst class" were observed. The presence of less effective teacher behaviors in these classes was verified. The less effective behaviors occurring at the highest frequency were associated with these dimensions: maintaining on-task behavior; warmth; task-oriented/business-like environment; and teacher expectancy. (KH)