<p>Teachers' beliefs about data use directly influence their decisions to use it. This study aimed to investigate the beliefs of K-6 teachers regarding Data-Based Decision Making (DBDM) and how their self-efficacy and anxiety influence their perceptions of using DBDM. Using Self-Efficacy theory as its theoretical framework, the research followed an explanatory sequential mixed-methods design with a survey and one-on-one interviews with teachers to help understand the quantitative results. Results showed that teachers' perceptions of efficacy and anxiety when navigating educational technology platforms to access and utilize data should not be grouped, as they are distinct. Four main themes emerged from the data analysis. These themes were Data Dashboard Navigation, Data, Connecting Data to Practice, and Frustration. The first three themes were factors that can potentially impact teachers' efficacy and anxiety with DBDM and provided insight into K-6 teachers' data use practices, beliefs, affective states, and barriers to using data in the classroom. The final theme, Frustration, found that teachers' efficacy, anxiety, and perceptions may be influenced by their frustration with different DBDM tasks.</p>