Emission and absorption spectra of (5% Er) BaY2F8were studied at 300, 77, and 4.2 °K. Stark‐level positions were determined from the liquid‐helium absorption spectra. Emission spectra were excited with a UV flash lamp and 1.53‐&mgr;m radiation from an Er:glass laser; in the latter case, the visible and near‐IR fluorescence of the Er3+ions was excited through a multiphoton upconversion process. The lifetimes of Er3+‐ion‐excited states were measured at 300 and 77 °K. Laser action was stimulated at 0.85, 1.73, and 2.796 &mgr;m in a (5% Er) BaY2F8laser rod using the transitions4S3/2→4IJ, whereJ=13/2, 9/2, and4I11/2→4I13/2, respectively. A Xe flash lamp was used for optical pumping. The latter two laser transitions were also pumped through upconversion of 1.53‐&mgr;m radiation of the Er:glass laser. The cross‐relaxation ion‐pair conversion coefficient for the4I13/2levels of the Er3+ions in BaY2F8was calculated to be &agr;=3.7×10−17cm−3 s−1.