This paper studies effects of income-based and collateral borrowing constraints on wealth accumulation andportfolios. We compare unconstrained and constrained behavior for different types of constraints and degrees of tightness.Income-based constraints can reduce or eliminate effects of earnings risk on wealth accumulation by constraining wealthadjustments to such risk. They can also reverse effects of risk aversion and of temperance on stockholding relative to thoseobtained in unconstrained models. Analogous results hold for collateral constraints, where risky assets play the dual role ofportfolio component and of collateral. Thus, samples containing borrowing-constrained households are likely to underplay or evenreverse the impact of risk aversion and of earnings risk expected on the basis of unconstrained models. This may help explain thefailure of empirical studies to uncover sizeable precautionary effects on wealth and on portfolios.