<p>Experience is considered a crucial but insufficient factor for noticing, as noticing requires identifying and attending to key moments in complex teaching situations and interpreting them through knowledge-based reasoning. Yet current research has paid relatively little attention to how early-career teachers who are learning to navigate the profession attend to and interpret content-specific issues. This study aims to contribute to the field by investigating what and how 207 U.S. teachers who are early in their teaching careers noticed when viewing authentic video clips of mathematics instruction, as well as the roles of their content knowledge and educational backgrounds in making sense of the instances they noticed. Our findings indicate that early-career teachers most often noticed issues related to mathematics pedagogy as noteworthy events and took an interpretive stance in making sense of them. Additionally, how teachers made sense of the attended events was closely tied to their robust understanding of the content, whereas indicators of educational preparation—such as the teacher preparation route and holding a mathematics teaching credential—were not.</p>