The Prison Litigation Reform Act requires prisoners to exhaust administrative remedies before challenging the conditions of their confinement in federal court. The question in this case is whether Congress intended to bar prisoners from going to federal court when they first present their claim to prison officials, as the PLRA requires, but have their claim rejected by prison officials on the ground that it was filed too late. This seemingly technical issue has real practical importance because many prison systems throughout the country have established very short filing deadlines for administrative claims.