This chapter focuses on current oscillations and interference phenomena in an attempt to provide an overview of progress in the field. The current oscillations have a finite spectral width and display temporal fluctuations which can be studied by examining the time dependence of the Fourier transformed current. The overall features of the observed current oscillations depend on crystal quality and in general on the coherence associated with the current carried by the collective mode. Current oscillations have been studied in the time domain by recording the time dependence of the current or voltage following a pulse excitation. The current oscillation phenomena which occur in driven charge density wave systems in the nonlinear conductivity region and associated interference effects in the presence of dc and ac drives are clear manifestations of a new type of collective transport phenomenon, carried by an electron-hole condensate.