Writing program administrators and other composition specialists need to know the history of writing assessment in order to create a rich and responsible culture of it today. In its first fifty years, the field of writing assessment followed educational measurement in general by focusing on issues of reliability, whereas in its next fifty years, it turned its attention to validity. Overall, the field has exhibited a tension between reliability and validity, with the latter increasingly being conceptualized as involving a whole set of considerations that need to be theorized. (Contains 15 notes.)