In this article, we explore the use of strengths interventions, defined as activities and processes that target the identification, development, and use of individual strengths, as an organizational tool to increase employee well-being. Engaging with one’s strengths is assumed to be a pleasant activity that elicits positive emotions like joy, pride, and gratitude, which, in turn, contribute to feelings of overall well-being and satisfaction. Building on this assumption, we hypothesized that participating in a strengths intervention leads to increases in general (i.e., psychological capital and satisfaction with life), and work-related well-being (i.e., increased work engagement and decreased burnout), and that positive affect mediates these effects. To test these hypotheses, we conducted a field experiment with a sample of N = 116 Dutch working people who were assigned to either an experimental group (participating in a strengths intervention) or a waitlist control group. All participants filled in a pre-intervention, post-intervention, and 1 month follow-up questionnaire. Results indicate that participating in a strengths intervention creates short-term increases in employee positive affect and short- and long-term increases in psychological capital. We did not find evidence for a positive, direct effect of the strengths intervention on satisfaction with life, work engagement, and burnout respectively, but we did find support for indirect effects via the mediator positive affect.