This new book, Processing Instruction: Theory, Research, and Commentary, edited by Bill VanPatten--a pioneer in processing instruction (PI)--is a refreshing presentation of 10 related and not widely available articles that illustrate the role of processing instruction in second language acquisition. The articles provide both historical and current context, as well as describe the influence of the input processing model on PI. The contents include empirical papers presenting new data that demonstrate both the theoretical and pedagogical threads of research. Aside from simply establishing where PI stands in the field of instructed SLA, the book addresses issues, such as processing instruction versus other types of instruction; the impact of processing instruction on various linguistic structures; the role of explicit information in instructional intervention; and the long-term effects of processing instruction. Each section of the book is highlighted by commentaries from noted researchers in instructed SLA. An attempt was made to include voices that offer critical perspectives on various issues of PI research. The book achieves an unusually balanced approach to a subject that has stirred debate in the field. Processing Instruction: Theory, Research, and Commentary will serve as an important source of information regarding research methodology and replication in second language acquisition. It will also be useful in graduate courses where students need exposure to research design and is especially useful for illustrating the usefulness of replication in SLA research.