This "Practitioner's Guide to Growth Models," commissioned by the Technical Issues in Large-Scale Assessment (TILSA) and Accountability Systems & Reporting (ASR), collaboratives of the "Council of Chief State School Officers," describes different ways to calculate student academic growth and to make judgments about the adequacy of that growth. It helps to clarify the questions that each model answers best, as well as the limitations of each model. This document is intended to support states as they address the challenges of evolving assessment and accountability systems. This guide does not promote one type of interpretation over another. Rather, it describes growth models in terms of the interpretations they best support and, in turn, the questions they are best designed to answer. The goal of this guide is thus to increase alignment between user interpretations and model function in order for models to best serve their desired purposes: increasing student achievement, decreasing achievement gaps, and improving the effectiveness of educators and schools. The report is divided into two parts. Part I, A Framework for Operational Growth Models, includes seven models: (1) Growth and Growth Models; (2) Growth: Beyond Status; (3) Different Ways to Slice the Data: Status, Improvement, and Growth; (4) What is a Growth Model?; (5) Growth Models of Interest; (6) Critical Questions for Describing Growth Models; and (7) Alternative Growth Model Classification Schemes. Part II, The Growth Models, includes seven chapters: 1: The Gain Score Model; (2) The Trajectory Model; (3) The Categorical Model; (4) The Residual Gain Model; (5) The Projection Model; (6) The Student Growth Percentile Model; and (7) The Multivariate Model. An appendix explains cross-referencing growth model terms. A bibliography is also included.