"Acting white" was once a label used by scholars, writing in obscure journals, to characterize academically inclined, but allegedly snobbish, minority students who were shunned by their peers. Now that it has entered the national consciousness--perhaps even its conscience--the term has become a slippery, contentious phrase that is used to refer to a variety of unsavory social practices and attitudes and whose meaning is open to many interpretations, especially as to who is the perpetrator and who the victim. This article presents the results of research conducted by the author to examine whether or not ethnographers were correct in identifying a distinctive acting-white phenomenon within African American and Hispanic communities. His analysis confirms that peer ostracism due to "acting white" is a vexing reality within a subset of American schools. He finds that the way schools are structured affects the incidence of the acting-white phenomenon, indicating that this social disease, whatever its cause, is most prevalent in racially integrated public schools. (Contains 2 figures.)