<p>Coworker friendships refer to interpersonal relationships between peers and overlap across work and personal domains of life. Prior research suggests that these relationships are beneficial in some ways and detrimental in others, and that they are characterized by divergent forms of social bonds (i.e., friendly or affective bond and work-related or instrumental bond), relational expectations, and norms. Yet, the processes through which coworker friendships influence employees’ work outcomes and well-being remains poorly understood. To illuminate the features of coworker friendships and the mechanisms through which they affect employees, I develop the Coworker Friendship-Resource (CFR) Model. Specifically, building from interaction ritual theory, I explore how features of friendship—nonwork socializing and self-disclosure with coworker along with the personal growth function (i.e., benefit or purpose) of the coworker relationship—simultaneously drain and replenish employees resources or energy by shaping work-nonwork (enrichment and conflict), affective (vitality), cognitive (psychological detachment from work), and relational (intrusion) mechanisms, and subsequent employee work behaviors, well-being, and relationship conflict. I also consider the contingencies affecting these pathways, including contextual work features and individual differences. Overall, the CFR model highlights the simultaneous benefits and burdens of coworker friendships for employees and organizations. To test the CFR model, I conducted a pilot study to validate new measures, a vignette experiment, and a two-wave field study. As a set, the results of the vignette and field studies revealed countervailing effects of the friendship features on resource gain and drain.</p>