The basic research problem was to ascertain the relationship between the concerns of the elementary school principal administering a mainstreaming program and the concerns of teachers teaching in one. The following questions were examined: (1) What specific stages of concern about the innovation were perceived by principals? (2) What specific stages of concern were perceived by teachers? (3) Was there a difference between the perceived concerns of principals and teachers? (4) Was there a relationship between selected demographic characteristics and stages of concern that principals perceived? (5) Was there a relationship between selected demographic characteristics and the stages of concern that teachers perceived? Seventy-six elementary school principals and 817 elementary teachers in northern Illinois were surveyed with the Stages of Concern Questionnaire and another questionnaire that was designed to gather demographic data. On the whole, principals were more concerned about the impact of the program on students and colleagues but teachers were more concerned about its impact on themselves. There was no clear pattern of how personal characteristics of principals affected or related to the stages of concern. Teachers with some background in mainstreaming viewed the concept more positively than did teachers without such a background. (Author/IRT)