The resonance enhanced multiphoton ionization (REMPI) spectra of I₂ and IBr have been recorded at room temperature in a static cell and in a supersonic-jet (circa. 20K). The results of both sets of data provide an interesting contrast between two similar, yet distinct species. The room temperature REMPI spectrum of I₂ has been recorded in the region 48000-75300cm^-1 using both linearly and circularly polarized light. Rydberg states (ns) up to n = 11, based on the [3/2]_g ionic core, and up to n = 8 based on the [1/2]_g ionic core, have been observed together with three 5d states based on each core. Of these, twelve states have been observed for the first time and six other states have been reassigned. Assignments have been made by comparing the observed molecular quantum defects with those of atomic iodine, by using band contour analysis and by measurement of polarization ratios. Polarization ratios which are widely different from those expected have been observed for some systems. Preliminary jet-cooled REMPI spectra revealed that some Rydberg states are homogeneously perturbed by high vibrational levels of one or more ion-pair states from the first ion-pair cluster. The REMPI spectrum of IBr has been recorded in the region 62500-55500cm^-1. In contrast to the I₂ (and BR₂) REMPI spectra, where Rydberg transitions dominate, strong transition to ion-pair states dominate the spectrum of the interhalogen IBr (and ICI). Pronounced resonance structure caused by coupling between the b's Rydberg state, observed for the first time, and the ion-pair states has been observed.