Mindfulness has received increased attention in organizational research and practice, with the majority of work focusing on the beneficial, buffering effects of trait mindfulness and mindfulness interventions. We extend work on mindfulness in the workplace by examining the causes and consequences of daily and momentary within-person fluctuations in state mindfulness. Grounded in theories of self-regulation, this research helps shed light on dynamic, everyday antecedents and outcomes of state mindfulness in work contexts. Specifically, we argue that increases in meaningful work perceptions activate mindful states, which in turn have important consequences for counterproductive work behavior (CWB). Using an experience sampling methodology, we examine dynamic fluctuations among nurses’ experiences of meaningfulness, mindful states, and CWB and find support for the indirect effect of meaningfulness on CWB through state mindfulness. Implications and future research directions are discussed in light of these findings.