The International Baccalaureate (IB) programme utilizes an inquiry-based multi-disciplinary approach and focuses on the teaching of critical-thinking skills. The IB programme is growing at a rapid rate within the United States, with the overall number of IB schools having more than doubled in the last five years. The purpose of the present study was two-fold: (a) to specifically focus on classroom instruction and students' behavior within Texas IB schools, and (b) to highlight the importance of systematic classroom observation as an evaluative method; in particular, the simultaneous use of three observation instruments to illustrate the importance of examining instruction from multiple perspectives. Systematic observations of 85 classrooms from eight Texas IB schools revealed that instruction in most of the schools was active, with teachers often engaging students, exploring new skills and key concepts, explaining, elaborating, and evaluating. Overall, the general instructional practices and student behaviors/activities observed were favorable and were higher than those found in similar classrooms in Texas schools. The amount of time that students were observed as being on-task was dramatically higher than the amount of student on-task time measured in other observational studies.