Abstract Objectives The present study examined potential sources of intra- and inter-individual differences in older adults’ control beliefs using a micro-longitudinal design. Method Older adults (n = 205) ranging in age from 60 to 94 (M = 72.70, SD = 6.72) completed 8 in-person testing sessions within 3 weeks which included assessments of control beliefs (Locus of Control and Perceived Competence), physical health (physical symptoms and sleep self-efficacy), stressors, emotional well-being (Positive Affect and Negative Affect), and cognition (basic cognition tests, everyday cognition, and memory failures). Results Multilevel models indicated that on days when older adults had higher sleep self-efficacy, more positive affect, and less negative affect, they also had more internal locus of control and higher perceived competence. Having stressors on the previous occasion was associated with lower internal locus of control on the subsequent occasion. Physical symptoms, everyday cognition, and memory failures could be predictive of locus of control for some older adults. Discussion Our findings showed the differentiated antecedents of locus of control and perceived competence, the unique role of sleep self-efficacy, positive affect, and negative affect in understanding antecedents of both, as well as the need to study well-being and cognition antecedents of control beliefs in future studies.