Elementary preservice teachers (n=185) in a blocked program of methods courses developed integrated thematic units focusing on social studies and science that viewed reading, language arts, and mathematics as tools students use to study the major content areas in the elementary school program: social studies and science. This was a complex task requiring both content and pedagogical knowledge. Those individuals subjects having the greatest difficulty conceptualizing and teaching the unit also sought the least help from course instructors. They had difficulty in constructing a unit rationale, choosing nontraditional assessments, and in choosing strategies other than lecture. Many could not initially integrate mathematics. Although cooperating teachers strongly encouraged the continued development of integrated thematic units they acknowledged that they were not sure that social studies was a major subject that should be taught daily and were uncertain that language arts, reading, and mathematics should be considered tools children use to learn. (Author/SG)