With the publication of the National Science Education Standards and the Benchmarks for Science Literacy, people now have a thorough idea of what an inquiry-based teacher is, and what he or she needs to do within a classroom in order to be successful. However, one major barrier in learning how to become an effective inquiry-based science teacher is classroom management. Research has shown that teachers often resist teaching inquiry-based science because they feel they will lose control of their classrooms. This is due, in part, to the fact that teachers often lack the procedural knowledge needed to manage a classroom where collaboration and scientific inquiry are emphasized. To address this and other related problems, this author developed the Science Management Observation Protocol (SMOP). SMOP is a classroom observation tool that can be used to assess a teacher's ability to manage an inquiry-based science classroom. The protocol provides valuable information on five different management issues that are especially important in inquiry-based science classrooms: (1) classroom characteristics and routines; (2) use of time and transitions; (3) collaboration among students; (3) safety; and (4) care and use of materials. This information supplies teachers with objective data rather than vague, undocumented "feelings" about the activities that take place during an inquiry-based lesson. These measurable details provide teachers with information they need to make decisions and initiate changes that will make them better managers of inquiry-based classrooms. (Contains 1 figure.)