Observations of the redshifted 21 cm line offer a promising probe of early radiation backgrounds. Anisotropies in the 21 cm signal arise from fluctuations in the IGM temperature, density, and neutral fraction and through the Lyman alpha flux. These fluctuations contain a wealth of information on the background radiation field at UV and X-ray frequencies. Before reionization, spatial variation in the Lyman alpha flux from the first sources imprints information about the source distribution on the 21 cm signal. Later, as the IGM is heated by X-rays, inhomogeneous heating leads to gas temperature fluctuations whose detection could constrain the luminosity and spectrum of the first X-ray sources. In this talk, I will discuss theoretical models for both of these mechanisms and outline the possiblities for detection with future experiments.