A recent one-on-one attempt by 17 Brown University students to "shadow" high school pupils for 1 day disclosed the bewildering complexity of high schools and the difficulties inherent in categorizing or evaluating them. This paper discusses the nature of this complexity. First, most high schools are densely populated work places. This "people density" is exacerbated by a frenetic schedule that allows little time or psychological space for teachers and contributes to feelings of isolation amid the crowd. Second, despite curriculum guides and standardized testing, each teacher is an individual entrepreneur creating his or her own world. Third, schools are synergistic places in which serious changes in one sector influence everything else in the school. A fourth obstacle to evaluating schools is their essential dailiness and the immediacy of the present moment. Understanding the nature of a particular school's tensions--or a particular classroom's tensions--is essential. Finally, there are variations in times and seasons when visiting schools. Evaluators must acknowledge the rich variety of any school, whatever its size. Schools must be seen whole, and their synergy must be understood. One must go well beyond published statements or school leaders' expressed policies or statistical analyses. Structured interviews must emerge out of a particular school's language and setting. Idiosyncracies must be carefully noted before generalizations and comparisons are attempted. (MLH)