A national survey of special education teachers was conducted to document current student-teacher ratios (STRs) and instructional arrangements used for students with mild handicaps. For this study, students with “mild handicaps” were those who received some instruction in the mainstream classroom. The 54.3% response rate included 141 elementary and 79 secondary teachers. The average STR was 4.7:1, with a range of 1:1 to 15:1. Minor differences were found as a function of the students' categorical designations and the elementary versus secondary distinction. Differences were found in the reported bases that teachers with higher (above 8:1) and lower (4:1 to 6:1) STRs used for selecting students for instructional groupings. The most frequently identified basis, regardless of category or grade level, was the student's level of academic performance. Survey results also indicated that teachers generally were unfamiliar with their local district guidelines for STRs and caseloads; 42% either stated that they did not know or left the item blank. Those who did respond indicated that guidelines for STRs and caseloads are ambiguous, not used, and/or difficult to apply. Implications of the findings and the need for additional research are discussed.