This paper presents a qualitative and quantitative analysis of a standard growth model modified to include precautionary saving motives and liquidity constraints. The primary goals are to provide an exposition of models where aggregate behavior results from market interactions among a large number of agents subject to idiosyncratic shocks, and to study the quantitative importance of individual risk for aggregate saving. The model is based on the Brock-Mirman growth model, modified to incorporate uninsured idiosyncratic risk and borrowing constraints. The analysis shows that the contribution of uninsured idiosyncratic risk to aggregate saving is modest, with the aggregate saving rate increasing by no more than three percentage points for moderate and empirically plausible values of risk aversion, variability, and persistence in earnings. However, for sufficiently high variability and persistence, the aggregate saving rate could increase by up to seven to fourteen percentage points. The paper also highlights the importance of asset markets in enabling consumers to smooth out earnings fluctuations, with optimal accumulation and decumulation of assets reducing consumption variability by about half and increasing welfare by about 14% of per capita consumption. Additionally, the model is consistent with certain features of income and wealth distributions, such as positive skewness, higher dispersion in wealth than income, and higher inequality measured by the Gini coefficient for wealth compared to income.This paper presents a qualitative and quantitative analysis of a standard growth model modified to include precautionary saving motives and liquidity constraints. The primary goals are to provide an exposition of models where aggregate behavior results from market interactions among a large number of agents subject to idiosyncratic shocks, and to study the quantitative importance of individual risk for aggregate saving. The model is based on the Brock-Mirman growth model, modified to incorporate uninsured idiosyncratic risk and borrowing constraints. The analysis shows that the contribution of uninsured idiosyncratic risk to aggregate saving is modest, with the aggregate saving rate increasing by no more than three percentage points for moderate and empirically plausible values of risk aversion, variability, and persistence in earnings. However, for sufficiently high variability and persistence, the aggregate saving rate could increase by up to seven to fourteen percentage points. The paper also highlights the importance of asset markets in enabling consumers to smooth out earnings fluctuations, with optimal accumulation and decumulation of assets reducing consumption variability by about half and increasing welfare by about 14% of per capita consumption. Additionally, the model is consistent with certain features of income and wealth distributions, such as positive skewness, higher dispersion in wealth than income, and higher inequality measured by the Gini coefficient for wealth compared to income.