This book tackles three choices that face developers of L2 writing assessments: defining L2 writing abilities; collecting evidence of those abilities (usually by getting L2 writers to write something); and judging their performance (usually by assigning a score or grade to it). It takes a historical view of how assessment developers have made those choices, how contemporary practices emerged, and of alternative techniques that have risen and fallen over time. The three sections each tackle one of these choices. The first considers the social functions that define L2 writing and assessment; the second relates how assessment tasks have adapted to changing conceptions of languages, writing, and assessment; and the third explores how scoring systems have evolved. Each section brings the reader up to date with current issues confronting writing assessment (both in large-scale testing and in language classrooms) before considering the new opportunities and challenges of the digital age. This book will be of interest to students, scholars and practitioners in language assessment, language education, and applied linguistics.