Several measurement assumptions were examined with the goal of assessing the validity of the Multidimensional Students' Life Satisfaction Scale (MSLSS), a measure of adolescents' satisfaction with their family, friends, living environment, school, self, and general quality of life. The data were obtained via a cross-sectional survey of 8,225 adolescents in British Columbia, Canada. Confirmatory factor and factor mixture analyses of ordinal data were used to examine the measurement assumptions. The adolescents did not respond to all the MSLSS items in a psychometrically equivalent manner. A correlated five-factor model for an abridged version of the MSLSS resulted in good fit when all negatively worded items and several positively worded items (the least invariant) were excluded. The abridged 18-item version of the MSLSS provides a promising alternative for the measurement of five life domains that are pertinent to adolescents' quality of life.