Intended for writing teachers and administrators of writing programs, this handbook is both an information source and a model for a staff development workshop on writing assessment. Section I reviews the history of the New Jersey Statewide Writing Test, while Section II describes the test format, content, and reporting procedures. After an evaluation of holistic scoring in Sections III and IV, Section V suggests ways of applying test results to strengthen student writing. The final two sections discuss curriculum changes, materials, and strategies to improve writing instruction. The entire handbook is organized around a sample agenda for a writing assessment workshop. Appendixes include descriptions of successful writing programs, sample writing topics, a list of publishers welcoming student writing, and information on ERIC documents on writing instruction. (MM)