Electron correlation is a result of the interaction of two or more electrons confined in a region of space, and may conveniently be treated under the formalism of configuration interaction (CI). Photoionization provides a rather direct experimental method for studying configuration interaction. The types of CI involved in the photoionization process can be divided into three categories: initial state configuration interaction (ISCI), final ionic state configuration interaction (FISCI), and continuum state configuration interaction (CSCI). This thesis deals with experimental studies which reveal how the various types of CI may become manifested in photoionization. The experimental methods utilized in this work are photoelectron spectroscopy (PES), electron impact spectroscopy (EIS), and time-resolved fluorescence spectroscopy. The EIS was carried out following the discovery that the UV lamp on a Perkin-Elmer photoelectron spectrometer could be utilized as a source of low energy electrons. The time-resolved fluorescence work utilized both the tunability and the time structure of the radiation available at the Stanford Synchrotron Radiation Laboratory (SSRL). A commercial photoelectron spectrometer equipped with a conventional UV lamp (Hei, Nei) was employed for some of the PES studies, and a novel time-of-flight photoelectron spectrometer was developed for the PES work performed using synchrotron radiation. The PES …