Many areas of study, from particle-surface interactions to magnetic properties of surfaces and thin films, can benefit from electron spin analysis. These experiments frequently employ Mott polarimeters. In the past, Mott polarimeters were bulky, and operated at high voltages (∼150 kV). Modern retarding-potential Mott polarimeters operate in the 20 kV range, and are small enough to be mounted inside a vacuum system. A new, ultra-compact Mott polarimeter is described here which occupies a significantly smaller volume than previous designs. This polarimeter, when equipped with a thorium target and operating with an accelerating potential of 25 kV obtained a figure of merit of ∼1.3 x 10-4, which is similar to the best values achieved by previous Mott polarimeters. Thus this design is well suited for a variety of applications involving angle- and/or energy-resolved polarization measurements.