The primary purpose of this study was to determine the influence of student teaching experience on four aspects crucially related to preservice teachers' ability to teach in the increasingly complex environments created by exceptional students: self-efficacy, outcome expectations, sources of information, and choice behavior or perceived ability to cope with students that present exceptional challenges in a full-inclusion regular education classroom;The study utilized a nonrandomized control group, pretest-posttest quasi-experimental design. The two groups were drawn from preservice elementary teachers attending a medium-sized state university in southern Minnesota during Spring Quarter of 1994. One group (n = 41) included students enrolled in elementary student teaching course. The other group (n = 37) included students enrolled in the Reading and Language Arts methods course who had not participated in student teaching;Data were collected at the beginning of the quarter and at the end of the quarter using an Inclusion Readiness Survey. This instrument included three major sections: Section 1-Personal Teaching Profile, Section 2-Sources of Efficacy Information, and Section 3-Depth of Experience;Results indicated that preservice teachers who complete a student teaching experience alter their self-efficacy judgments and become more positive about including students with differing ability levels in their regular education classrooms. Student teachers are more likely to choose to work in a full-inclusion teaching situation when their judgments about their capability to teach in this situation, expected outcomes for all students, and experiences with a wider range of student abilities are more positive. Student teachers who are more positive about their personal ability (self-efficacy) to teach students with differing ability levels also hold higher outcome expectations for all students' achievement and are more positive about their student teaching experiences (sources of information). The student teachers' judgments about self-efficacy, outcome expectations, sources of information, and ability to cope were significantly less positive as the description of the student's cognitive, behavioral, and physical ability became more severely impaired.