Flow at work is a dynamic experience of strong absorption and connection in a work-task, an intrinsic motivation to do what one is doing, and a sense of enjoyment that comes from meeting the challenges that arise. Its relevance to optimal teacher functioning is well documented, as have the frequent findings showing that educators experience flow at work often. Although theories suggest a mutually reinforcing association between flow and strengths use, and short-term experience sampling studies find support for such positive relationships, studies have not tested the inter-relationship of flow at work and strengths use prospectively over long time periods. Using a panel of school staff (N = 319) the current study investigated flow and personal strength use measured five times over a three-year period. Although flow and strengths were correlated within each time point, cross-lagged analyses did not find flow as predictive of strength use nor strength use as predictive of flow. Results point to the complexities of understanding dynamic psychological processes over time, the impact of time scales in which dynamic effects appear, and the importance of contextual factors. We consider implications for measuring and supporting wellbeing among school staff, when taking into account its dynamic nature.