Recent progress toward understanding the processes taking place in dye-sensitized nanocrystalline solar cells (DSC) is reviewed, and some areas characterized by controversy or poor understanding are highlighted. The thermodynamic and kinetic criteria for successful cell design are outlined, and experimental results obtained by a range of methods for characterizing the stationary and dynamic properties of DCS are discussed. These methods include direct measurement of the quasi-Fermi level using an indicator electrode and charge extraction measurements to determine the energetic distribution of electron traps in the nanocrystalline oxide. The influence of electron trapping on dynamic measurements of electron transfer and transport is discussed within the framework of the quasistatic assumption, and a new assessment of the electron diffusion length in the DSC is given, which suggests that collection of photoinjected electrons should be considerably more efficient than previously assumed.