Over the past 14 years, AEA's Oral History Project Team (Robin Lin Miller, Jean A. King, Valerie Caracelli, and Melvin M. Mark) has conducted interviews with individuals who have made signal contributions to evaluation theory and practice, tracing their professional development and contextualizing their work within the social and political climates of the time. By documenting the professional evolution of those who have contributed to the ways in which people understand and practice evaluation in the United States today, the team is creating an oral genealogy of the field of program evaluation. The authors also hope to capture the spirit of the times in which these individuals' ideas and interests developed. Robert E. Stake began as a specialist in psychometrics and instructional research. His focus evolved over the years to a specialization in program evaluation theory and practice, including naturalistic or ethnographic field study, particularly of classrooms. Among his many contributions are the countenance model of educational evaluation (1967), responsive evaluation (1974), and "The Art of Case Study Research" (1995). Stake's writings and thinking in program evaluation have influenced the work of numerous scholars in the field. He is well known as a creator of the metaphor that captures the distinction between formative and summative evaluation: ''When the cook tastes the soup, that's formative; when the guests taste the soup, that's summative.''