Measurements of the absorption spectrum of F centers in CsI reveal structure similar to that of the F band in CsBr. Bands like the L bands in other alkali halides have been observed in CsBr and CsI. In CsBr these L bands exhibit structure similar to that of the CsBr F band. The emission of F centers in CsCl, CsBr, and CsI has been measured. The emission spectra are double Gaussian, peaking at 1.255, 0.910, and 0.740 eV in CsCl, CsBr, and CsI, respectively. The full widths at half-maximum are 0.245, 0.184, and 0.140 eV, respectively. The emission in CsBr is excited with constant quantum efficiency in all parts of the F band. The lack of structure in the emission bands can be explained by either of two descriptions of the excited F center after relaxation of the lattice has occurred. Dichroism of the M band in CsBr indicates these centers have ⟨100⟩ transition-dipole axes as expected for the van Doorn-Haven model of the M center. Other M-center transitions lie under the long-wavelength part of the F band. A large number of F-aggregate bands have been found.