Using a calibrated, collective life-cycle portfolio choice model for a dual-income couple, we show that an increase in the ability to share risk within the household due to a mean-preserving spread in the partners’ coefficients of relative risk aversion leads to a substantial increase in financial risk-taking. Importantly, we show that risk sharing has a larger economic impact on portfolio choice than risk diversification. While unitary models usually do not fully replicate the optimal portfolio choice of collective models, we propose approximations that work reasonably well for moderate background risk. We provide strong empirical support for our key findings.