A single crystal of 5% Pr3+ in LaCl3 was grown by Stockbarger’s method and its absorption spectrum at 77° K. recorded in the region 4200–5400 Å on a grating spectrograph having a dispersion of 5 Å/mm. in the first order. Polarization of the absorption lines has also been obtained. In the group of lines arising from1I6 ←3H4 transition, six more lines in addition to the four previously known have been observed. Satisfactory analysis of all these ten lines is given. One additional Stark level in1I6 is established at 21407 cm.−1 withμ=1. For a few lines the polarization results obtained here do not agree with those of previous workers but fit in satisfactorily in the analysis.