"We document the loan provisions in 401(k) savings plans and how participants use 401(k) loans. Although only about 22% of savings plan participants who are allowed to borrow from their 401(k) have such a loan at any given point in time, almost half had used a 401(k) loan over a longer, seven-year horizon. The probability of having a loan follows a hump-shaped pattern with respect to age, job tenure, account balance, and salary, but conditional on having a loan, loan size as a fraction of 401(k) balances declines with respect to these variables. Participants are less likely to use loans in plans that charge a higher interest rate, and loans are smaller when plans allow fewer simultaneously outstanding loans, impose a shorter maximum possible loan duration, or charge a lower interest rate."