In this report, we describe the development of an extension of the SuccessNavigator® assessment for late high school settings. We discuss the assessment's conceptualization and support its application with psychometric studies detailing scale development in terms of structural analyses, reliability, and several other aspects of validity. High School SuccessNavigator (HSSN) is an assessment of students' noncognitive and academic skills important to their preparation for transitioning to higher education. The assessment provides a holistic review of students' strengths and potential areas for improvement, and it was designed for use by counselors and administrators to aid their work in engaging students to facilitate skill development. The primary aim of HSSN is to provide a standardized metric by which to direct individualized support to students as they ready themselves for postsecondary enrollment.