This paper investigates how mathematics instructors' recognition of the professional obligations of mathematics teaching varies based on their institutional environment, specifically whether they teach high school or college mathematics. Using an instrument that measures instructors' recognition of four hypothesized professional obligations, we surveyed 471 US high school mathematics teachers and 239 university mathematics instructors to measure the extent to which they recognized professional obligations when evaluating the appropriateness of certain instructional actions. After testing measurement invariance of four item sets, each of which measures one of the four hypothesized professional obligations--disciplinary, institutional, interpersonal, and individual obligations-, we compared the instructors' recognition of each of the four obligations between the two groups. We found that university instructors recognized the institutional obligation more than high school teachers, while recognizing the individual and interpersonal obligations significantly less. This investigation provides insight into the variation in the nature of mathematics teaching practice across different levels of schooling.