The Department of Energy Inertial Fusion Division has initiated a study to determine the requirements for a national Laboratory Microfusion Facility (LMF). The candidate driver technologies must demonstrate an on-target energy capability in the 3- to 10-MJ range, with the pulse shape, duration, wavelength, etc., needed for high target gain. Projections from available data indicate that this amount of energy delivered to a fusion target could lead to high gain (25–100). Studies at Los Alamos aimed at defining the size, cost, and performance of megajoule-class fusion facilities show that the large extrapolation for the drivers and targets from present capabilities has significant cost and performance risks. Los Alamos has identified an intermediate step at the 100-kJ level that would permit the demonstration of krypton fluoride (KrF) laser and target physics scaling and would determine the best illumination geometry and target design through experimentation. This intermediate facility would be used to quantify target behavior with accurately shaped pulses of very short wavelength light. The advantages of broad bandwidth and induced spatial incoherence in suppressing target instabilities would also be assessed. The purpose of this paper is to describe the design of the Los Alamos 100-kJ Laser Target Test Facility. The critical design requirements and issues will be discussed and the design logic used to achieve the required performance for large KrF single-pulse inertial confinement fusion facilities will be described.