Multiyear procurement (MYP) and block buy contracting (BBC) are special contracting mechanisms that Congress permits the Department of Defense (DOD) to use for a limited number of defense acquisition programs. Compared to the standard or default approach of annual contracting, MYP and BBC have the potential for reducing weapon procurement costs by a few or several percent. Under annual contracting, DOD uses one or more contracts for each years worth of procurement of a given kind of item. Under MYP, DOD instead uses a single contract for two to five years worth of procurement of a given kind of item without having to exercise a contract option for each year after the first year. DOD needs congressional approval for each use of MYP. There is a permanent statute governing MYP contracting10 U.S.C. 2306b. Under this statute, a program must meet several criteria to qualify for MYP. Compared with estimated costs under annual contracting, estimated savings for programs being proposed for MYP have ranged from less than 5% to more than 15%, depending on the particulars of the program in question, with many estimates falling in the range of 5% to 10%. In practice, actual savings from using MYP rather than annual contracting can be difficult to observe or verify because of cost growth during the execution of the contract due to changes in the program independent of the use of MYP rather than annual contracting. BBC is similar to MYP in that it permits DOD to use a single contract for more than one years worth of procurement of a given kind of item without having to exercise a contract option for each year after the first year. BBC is also similar to MYP in that DOD needs congressional approval for each use of BBC.