The Spectrum Analysis option (Option 49) in the MS464XB allows for convenient spectral domain measurements of quantities such as harmonics, spurs, other distortion products, and general frequency content of a variety of a devices. The user interface is configured in a way closer to that of classical spectrum analyzers, but a number of VNA-like behaviors are available, including many different sweep modes, source drive, power and receiver calibrations, multiple receiver measurements, and multiple source control for complex frequency plans. This chapter describes the operational characteristics of this application along with some example measurements.