All research on curriculum development incorporates implicit assumptions about the nature of persons and the nature of learning. These assumptions fall into two major categories: (1) psychological assumptions, based on empirical descriptions; and (2) logical (conceptual) assumptions, which give explanatory accounts of meaning. Most curriculum theory has depended on the empirical assumption that human behaviors are predictable because they are observable, and that students are "learners." This assumption leads to a curriculum development focused on training people to act in certain ways. In today's increasingly complex, multicultural society, however, curriculum developed for "learners" becomes insignificant at levels beyond training in basic processes. Conceptual curriculum theorizing recognizes students as "persons": human beings with freedom, value, and dignity. Curriculum grounded in the concept of "person" is flexible, humanizing, and able to account for unanticipated learning outcomes. Effective curriculum development can use the strengths of both types of assumptions by working from a logical or conceptual assumption about "persons," delineating necessary conditions of that concept, employing existent curricula, and evaluating them for necessary conditions as well as "learner" behaviors related to the subject matter, discipline, or conceptual base. (IW)