The Employee Benefit Research Institute (EBRI) and the Investment Company Institute (ICI) have been collaborating for the past two years to collect data on participants in 401(k) plans. This effort, known as the EBRI/ICI Participant-Directed Retirement Plan Data Collection Project, has obtained data for 401(k) plan participants from certain of EBRI and ICI sponsors and members serving as plan recordkeepers and administrators. The report includes 1996 information on 6.6 million active participants in 27,762 plans holding nearly $246 billion in assets. The data include demographic information, annual contributions, plan balances, asset allocation, and loans, and are currently the most comprehensive source of information on individual plan participants. In 1996, the first year for which data are ready for analysis, the EBRI/ICI database appears to be broadly representative of the universe of 401(k) plans. Key findings include: for all participants, 44.0 percent of the total plan balance is invested in equity funds, 19.1 percent in employer stock, 15.1 percent in guaranteed investment contracts (GICs), 7.8 percent in balanced funds, 6.8 percent in bond funds, 5.4 percent in money funds, 0.8 percent in other stable value funds, and 1.0 percent in other or unidentified investments. This allocation implies that over two-thirds of plan balances are invested directly or indirectly in equity securities. Asset allocation varies with age. For instance, on average, individuals in their twenties invested 76.8 percent of assets in equities and only 22.1 percent in fixed-income investments. By comparison, individuals in their sixties invested 53.2 percent of their assets in equities and 45.9 percent of assets in fixed-income investments. Investment options offered by 401(k) plans appear to influence asset allocation. For example, the addition of company stock substantially reduces the allocation to equity funds and the addition of GICs lowers allocations to bond and money funds. Employer contributions in the form of company stock affect participant allocation behavior. Participants in plans in which employer contributions are made in company stock appear to decrease allocations to equity funds and to increase the allocation of company stock in self-directed balances. The average account balance (net of plan loans) for all participants is $37,323. The balances, however, represent only amounts with current employers and do not include amounts remaining in the plans of prior employers. Nor do the balances indicate what savings would be in a "mature" 401(k) plan program. The average balances of older workers with long tenure at one employer indicate that a mature 401(k) plan program will produce substantial account balances. For example, individuals in their sixties with at least 30 years of tenure have average account balances in excess of $156,000; those in their fifties have balances in excess of $117,000.