The article examines Sparta’s influence on the treatment of luxury and wealth in early-modern republican thought, analyzing three key thinkers: Francesco Guicciardini, Montesquieu and Abbé de Mably. In this view, unnecessary wealth and, particularly, consumption over a certain limited level, is a pernicious extravagance that harms virtue and leads to corruption of the commonwealth that allows it. Both the direct influence of the Spartan example and the correlative Platonic ideal, inspired by the Lacedaemonians, are analyzed; the influence of Plutarch is emphasized. Special attention is given to the distinction between the Platonic account, with the twin dangers of both wealth and poverty, and a simpler, binary opposition of virtuous poverty vs. corrupting wealth. Guicciardini’s and Mably’s views are closely examined; for Montesquieu, the article traces the decisive role Plato plays in Montesquieu’s account of luxury, and analyzes his almost unknown work, Dialogue de Xantippe, showing the importance of Sparta for Montesquieu’s idea of republic.