The goal of this practice guide is to offer educators specific, evidence-based recommendations that address the challenges of teaching students in grades 6-12 to write effectively. This guide synthesizes the best publicly available research and shares practices that are supported by evidence. It is intended to be practical and easy for teachers to use. The guide includes many examples in each recommendation to demonstrate the concepts discussed. Throughout the guide, examples, definitions, and other concepts supported by evidence are indicated by endnotes within the example title or content. For examples that are supported by studies that meet WWC design standards, the citation in the endnote is bolded. Examples without specific citations were developed in conjunction with the expert panel based on their experience, expertise, and knowledge of the related literature. This guide provides secondary teachers in all disciplines and administrators with instructional recommendations that can be implemented in conjunction with existing standards or curricula. Teachers can use the guide when planning instruction to support the development of writing skills among students in grades 6-12 in diverse contexts. The following are appended: (1) Postscript from the Institute of Education Sciences; (2) About the Authors; (3) Disclosure of Potential Conflicts of Interest; and (4) Rationale for Evidence Ratings.