The purpose of this study was to uncover the degree to which in-service teachers understand sociomathematical norms and the nature of that understanding without having to enter and observe their classes. We therefore developed five classroom scenarios exemplifying classroom interactions shaped by certain sociomathematical norms. We then administered these scenarios to in-service elementary school and grade 5-12 mathematics teachers and collected their written responses. We also collected data about what teachers believe about sociomathematical norms through a Likert-type questionnaire. We then analyzed the data using quantitative and qualitative techniques. First, the findings suggest that the teachers' understanding of sociomathematical norms is neither dependent on the level of schools teachers teach, or their background or demographic characteristics such as number of years they spent in teaching, specialty area, faculty graduated, highest degree earned, and gender. Second, what teachers believe about sociomathematical norms seem to be not parallel to how they analyze the scenarios illustrating sociomathematical norms. Third, use of scenarios was helpful in revealing how teachers think about sociomathematical norms. Finally, there are three cross-cutting themes to which all the teachers referred in common for all sociomathematical norms: opposition (opposition to the core of the norm), social facilitator (considering all targeted norms as supporting and regulating the classroom social environment) and condition-based (believing that interactions given in scenarios are only possible under certain conditions).