Interfacial electron transfer is the most fundamental process driving all imaging technologies. The advent of ultrafast lasers has led to the development of novel experimental techniques to probe such dynamics. This article presents five time domain spectroscopies that allow direct measurement of different segments of the electron trajectory across a heterogeneous interface. Electro-optic sampling measures field-assisted transport of carriers to the surface. Time-resolved two-photon photoemission enables measurement of electron relaxation at surfaces. Timecorrelated single-photon counting, transient grating, and transient absorption techniques are implemented to determine electron transfer rates at interfaces. With these real-time approaches, the primary photophysical and photochemical processes at semiconductor/liquid interfaces and dye-sensitized semiconductors can be studied directly. The new information forthcoming from such studies is that electron transfer processes can be extremely fast at surfaces, in a range approaching adiabatic coupling conditions between the delocalized bond states and discrete molecular donor or acceptor states. This observation leads to a new conceptual framework for understanding photoinduced interfacial charge transfer processes.