Photodetachment is a fundamental ionization process by which electrons
are ejected from negative ions following the absorption of photons. E
lectron correlation plays a more enhanced role in photodetachment than
in photoionization. Experimentally measured photodetachment cross sec
tions serve to guide theory since they constitute sensitive tests of t
he appropriateness of wavefunctions used in calculations. The status o
f interacting beam measurements of photodetachment cross sections is r
eviewed.