This chapter describes creation and testing of procedures and instruments for use in international comparative research. It describes how the authors began their work with no existing measures of the theoretical concepts, and worked to construct and test a battery of measures for use. The chapter briefly explains the developmental model and its basic propositions about social change. It describes the organizational approach and initial steps in designing projects in several countries. The chapter explains how the authors used the experience and knowledge accumulated from their work in individual countries to prepare questionnaires and protocols for use in deliberately comparative projects. It discusses specific problems they encountered, along with lessons learned. The chapter provides preliminary evidence of the degree to which the authors were successful in measuring aspects of developmental thinking. Finally, it discusses the implications of the authors’ experience for other researchers who may design international data collections.