This manual contains information about the American College Test (ACT) Plan® program. The principal focus of this manual is to document the Plan program's technical adequacy in light of its intended purposes. This manual supersedes the 2011 edition. The content of this manual responds to requirements of the testing industry as established in the Code of Professional Responsibilities in Educational Measurement, the Standards for Educational and Psychological Testing, and the Code of Fair Testing Practices in Education. ACT regularly conducts research studies as part of the ongoing formative evaluation of its programs. These studies are aimed at ensuring that the programs remain technically sound. Information gleaned from these studies is also used to identify aspects of the programs that might be improved or enhanced. The information reported in this manual was derived from studies that have been conducted for the Plan program since its inception. ACT will continue to conduct research on the Plan program and will report future findings in updated versions of this manual. This manual is organized into the following chapters: (1) The ACT Plan Program; (2) The ACT Plan Tests of Educational Achievement; (3) ACT's College Readiness Standards and College Readiness Benchmarks; (4) Technical Characteristics of the ACT Plan Tests of Educational Achievement; (5) The ACT Plan Interest Inventory and Other Program Components; and (6) Reporting and Research Services.