The shelf life of dried beans depends on their storage conditions. In general, beans will last longer when stored in dark, cool places and in sealed containers than they will in the plastic bags in which they are sold.
When stored in normal polyethylene (food-grade) bags, beans will last at least one year.
According to Randy Duckworth, executive director of the U.S. Dry Bean Council, beans can last two years or more when sealed in a container and stored in a cool, dry place.
Light causes beans to fade and oxygen may make them go rancid. Storing beans in Mylar bags or #10 cans with oxygen absorbers will help them last 10 years or more, according to the Utah State University Cooperative Extension.
In a 2005 study by Larson et. al., pinto beans stored for 30 years were still deemed acceptable for emergency use (if not delicious).
Although there have been no studies specific to beans, the USU Cooperative Extension estimates that beans stored for long periods of time--upwards of five years--would lose all of their vitamin and mineral content. In addition, very old beans can become too dried out to absorb water properly.