An observational study of school principals confirms findings from earlier Australian and U.S. studies that emphasized the brevity, variety, and fragmentation of principals' work. Three secondary school principals in Victoria (Australia)--one in a public school and two in private schools--were observed for three weeks each. The study found that the principal's job is characterized chiefly by uncertainty, variety, brevity, discontinuity, and "invisibility." The three principals worked long hours, used a range of communication media, spent most of their time in interpersonal contacts, frequently changed location from preceding activities, often worked unseen by other school staff (and hence "invisible" to them), suffered frequent interruptions, and spent much of their time involved in affairs external to the school, often with nonsubordinates. The author concludes that principals' work should not be too tightly scheduled, since the core of the job involves organizational communication through interpersonal contacts, and that principals should have skills in handling uncertainty. (RW)