In The Political Economy of Progress, Joseph Persky argues for seeing John Stuart Mill as a consistent ‘radical’ with much to offer modern ‘radical’ political discourse. In this article, I further this claim with consideration of Mill's political philosophy, as well as his political economy. Exploring Mill's commitment to radical reordering of the economy, as well as emphasizing his commitment to egalitarianism; his historically nuanced view of ‘the progress of justice’; and his desire for a transformation of social (and economic) relations allows us to see more clearly how Mill's radicalism was a specific species of socialism. That is, Mill's early radical enthusiasm for the ideals of ‘liberty, equality and fraternity’ is also to be seen in his later socialism. Recognizing his ‘radicalism’ as a species of socialism allows greater understanding of the depth, importance and ‘radicalism’ of Mill's desired socialist reforms.