Results are shown demonstrating the application of the interfacial force microscope to a study of the micro-scale mechanical properties of an extreme example of a viscoelastic material, one that is often referred to as a "solid liquid." Experiments involve relaxation measurements taken over a range of deformations, to establish linearity, and scaled according to the optically determined contact radius. In addition, the data is Fourier analyzed to obtain the frequency response of both the real and imaginary components of the shear modulus. The results from such an analysis of a single 3s measurement are shown to be in remarkable agreement with published results from a series of single-frequency measurements using a classical rheometer. (c) 2005 Wiley Periodicals, Inc.