A two-laser multiphoton ionization (MPI) technique is used to measure the lifetime and ionization potential of the lowest excited Rydberg state of 1,4-diazabicyclo[2,2,2]octane (DABCO). In this method one laser causes a two-photon transition to the excited state, and a second laser, at variable time delays from the first, ionizes only the excited state molecules. Good agreement is found between the fluorescence lifetime of this two-photon state and the lifetime determined from the ionizing pulse delay. By scanning the ionizing laser wavelength at a fixed time delay, the ionization threshold is obtained. The dual-beam MPI threshold is sharper than the onset of the photoelectron spectrum. This is due to the fact that transitions between Rydberg levels and the ionization continuum (which determine the shape of the threshold in this technique) are more Franck-Condon allowed than the transition between the ground state of the molecule and the ground state of the ion (observed in the photoelectron spectrum). This two-year MPI method, which requires neither fluorescence, vacuum UV nor photoelectron equipment, should be applicable to a wide range of molecules. A simple qualitative picture of DABCO MPI dynamics has also been constructed from an analysis of the dependence of the fluorescence intensity and the delayed ion current on the laser light intensity. Single-laser MPI spectroscopy is shown to be limited by competition between ionization and dissociation or other quenching processes in the levels preceding the ionization continuum. The dual-beam MPI technique can be used in such a manner as to bypass dissociative states.