This is a method for planning tests of unassembled subsystems to estimate system reliability at a given confidence level. It is useful when subcontractors design and demonstrate their own subsystem's reliability. The full six-part definition of reliability is used. This includes emphasis on the level of confidence associated with the system reliability estimate. An example is given for a system with subsystems arranged in series. The subsystems have exponentially distributed lives. Charts for planning and plotting the progress of a test are provided for 0 to 12 failures at the 50%, 70%, 90%, and 99% confidence levels.