Despite the popularity of the ‘pay it forward’ (PIF) concept in textbooks and popular culture, to date, no study has tested the effectiveness of a brief, one-time PIF activity on the well-being of those who do good and those who receive good. To test this, 83 undergraduates (‘givers’) performed random kind acts for 1.5 h. PIF resulted in a wide range of well-being benefits for givers (e.g. greater positive and lower negative affect), with females showing greater positive affect benefits. Receivers of kindness (N = 1014) also benefited as evidenced by greater smiling behavior and more sincere smiles vs. controls (N = 251). Of the 48 receivers who completed a follow-up online questionnaire, the majority indicated that they would also PIF, with almost 40% indicating that they already had. Results indicate that a one-time brief PIF intervention can have broad benefits for those involved.