The purpose of the present study was to test the factor structure of the Students' Life Satisfaction Scale (SLSS) using confirmatory factor analysis, including tests of measurement invariance across gender. Data from a total of 921 middle school students (50.9% females, ages 11-15) were analyzed. Single group analyses showed that a modified one-factor model (with one residual covariance for the female group, and with two residual covariances for the male group) fit the data of each gender group adequately. Sequential multi-group analyses established the full scalar invariance, as factor loadings and factor intercepts were invariant across the male and female groups. These findings supported the use of the summed total (or average scores based on the summed total) from the scale to represent the levels of adolescents' overall life satisfaction and the combination of the responses from male and female adolescents. However, we recommend that researchers control the measurement errors (e.g., correlated residuals between items) before conducting further analysis.