The androgen receptor (AR) is the central component of a dynamic conformational and interaction cascade initiated by androgenic hormones. AR function can be modified by cellular inputs not examined in test tube studies of AR action. Thus, there is a need to measure AR conformation and biochemistry directly within the cell where the intracellular locations, levels and availability of the hormone, AR, AR-interacting factors, DNA-binding sites, enzymes that modify those components of AR action, and factors that compete for the formation of functional AR-cofactor complexes may affect AR action. The dynamic nature of the AR functional cycle itself may introduce temporal fluctuations in factor status and location to affect AR output in the intact cell. This chapter focuses on the method of Förster resonance energy transfer which uniquely has the resolving power and ability to directly measure the conformation and biochemistry of AR signaling in living cells.