Light-curves were obtained of 20 Massalia at phase angles ranging from near 0 to 20 . The amplitude of the light-curve appears to have changed from 0.17 to 0.23 mag. over the observed interval, March 27- May 15, 1955. For phases between 7 and 20 the phase factor was 0.03 mag/degree, but at phase angles smaller than 7 the factor was larger. The synodic period of rotation was found to be 5h5rn53s + 1 .