Self-regulated learning (SRL) is a cognitive and metacognitive process through which students develop the self-awareness necessary to direct their learning based on their needs to reach a desired outcome. Despite 40 years of literature, SRL has no singular definition, as it is often used in domain-specific research that is not always transferable to other fields. Regardless, much of the literature speaks to the importance of SRL regarding academic success. This paper details the development of an SRL instrument designed to identify key self-regulatory constructs in an undergraduate introductory physics classroom. Confirmatory factor analysis supported a four-factor model measuring Planning, Time & Environment Management, Comprehension Monitoring & Evaluation, and Peer Learning & Help-Seeking as unique facets of self-regulated learning. While most behaviors did not significantly evolve over one semester, students reported significantly lower scores on the Comprehension Monitoring & Evaluation factor between the beginning and end of the semester. Higher performing students, as measured by their average homework grades, scored significantly higher on the Time & Environment Management factor and the Peer Learning & Help-Seeking factor at both time points. Additionally, SRL behaviors were significantly predicted by personality facets from the Big Five Inventory, with Conscientiousness, Extraversion, and Openness being the most related to certain behaviors.