<p>Spousal cooperation is considered an important intra-household factor that improves wellbeing, yet its role in shaping diets and nutrition remains underexplored. Here, we combine a lab-in-the field experiment with survey data from Cameroon to analyze how spousal cooperation relates to household, children’s, and women’s dietary quality. Spousal cooperation is measured in terms of husband’s and wife’s budget allocations to a public goods game. Regression results reveal a robust U-shaped association: the marginal effect of cooperation on dietary quality is negative but declining in absolute magnitude for levels of cooperation from 0 to 0.7, at which point it becomes positive. That no cooperation is associated with better dietary outcomes than low and medium cooperation is unexpected. Possibly, no cooperation reflects separate spheres between husband and wife, which may not always be bad for dietary outcomes if women have own income that they can spend on healthy nutrition for their family. In contrast, low to medium cooperation may reflect role ambiguity and conflict, resulting in lower dietary quality. High cooperation may indicate more trust and harmony between spouses, which can plausibly lead to better dietary outcomes. Some of our findings challenge conventional wisdom. Further research is needed to explain the underlying mechanisms. This should also include work on how to measure the various nuances of spousal cooperation that likely matter in different contexts.</p>