Although person-centered planning is a popular approach in the field of developmental disabilities, there has been little systematic assessment of its process and outcomes. To measure person-centered planning, we developed three instruments designed to assess its various aspects. We then constructed variables comprising both a Process and an Outcome Index using a combined rational–empirical method. Test–retest reliability and measures of internal consistency appeared adequate. Variable correlations and factor analysis were generally consistent with our conceptualization and resulting item and variable classifications. Practical implications for intervention integrity, program evaluation, and organizational performance are discussed.