Despite considerable attention in the literature, existing studies analyzing the effect of left governmental power on inequalities suffer from three main limitations: a privileged focus on economic forms of inequality at the expense of political and social ones, inaccurate measurements of left governmental power, and the analyses’ narrow time spans. This article addresses such concerns through a comparative longitudinal analysis where the impact of left governmental power on different measures of political, social, and economic inequalities is investigated in 20 Western European countries across the last 150 years. Data show that, consistent with previous literature, the Left in government has significantly reduced most forms of inequalities. However, the equalizing effect of the Left in government has decreased over time and has become not significant since the 1980s. The Left is today incapable of accomplishing its historical mission of reducing inequalities. The article discusses the rationale and implications of these findings.