Both critics and defenders tend to regard structural-functionalism as a single school with a distinct identity and a common strategy. This paper argues that the illusion of unity has obfuscated the debate. It suggests that structural-functionalism harbors at least two quite different approaches. While both are “legitimate,” they lead to different conclusions and different vulnerabilities. Thus, it matters whether one is primarily concerned with thestructural partor thesystematic whole. In each case there are advantages and disadvantages, but charges of Panglossian unity, illusions of indispensability, static analysis, and ideological conservatism do not apply equally to both. Each is exposed to biases, but the biases are not the same.