A major concern regarding polarization is whether its effects can spill over beyond the political realm and affect our everyday interactions, compromising our ability to work together and collaborate in situations where both sides can achieve mutual gains. This paper investigates how affective polarization influences cooperation across political divides through a behavioral experiment conducted in the United States, Brazil, and Spain. Participants were asked to engage asynchronously in a simple one-shot task: converting into capital letters either a salad recipe or a political text written by another participant. The experiment manipulates several factors: whether the other participant supports the respondent’s most liked or disliked political party, the type of text (political or apolitical), and the rewards for cooperation (altruistic, individualistic, or a contribution to a public good). The results consistently show that cooperation decreases substantially when participants are informed that their partner supports their most disliked political party. This negative effect is observed across all three countries, although its magnitude varies. However, the detrimental effect of polarization on cooperation is mitigated, though not eliminated, when collaboration contributes to a public good. Among those who choose to cooperate, we also find that task quality improves with material rewards but declines when political texts are involved. These findings demonstrate that the effects of affective polarization extend beyond political behavior to influence fundamental social interactions, while also identifying factors that mitigate the extent to which partisan animosity undermines cooperation. Understanding these dynamics is critical for fostering collaboration in increasingly polarized societies.