This thesis describes and analyses the path of structural change in the Senegalese economy from around the abolition of slavery in French-ruled insular Senegal in 1848 to the time of structural adjustment in 1979. A study of the economics of urban slavery in mid nineteenth-century Senegal uses the structure of slave prices to argue that urban growth in nineteenth century West Africa was constrained and conditioned by the existence of land abundance in the countryside and a highly seasonal potential labour force. I argue that urban inequality in these economies is driven by the accumulation of rents to those who can command scarce and inelastically supplied resources, like urban land, permanent and skilled labour, and credit. As Dakar—Senegal’s most important city—grew, it drew upon reserves of low-skilled labour in the countryside. Many migrants moved to Dakar seasonally, taking advantage of the possibilities of the urban economy during the long dry season. Male workers born in Dakar were much more likely to obtain well-paid, skilled work than migrants; upward social mobility was also relatively low by contemporary standards. This urban growth was rapid, but costly: a large share of national capital formation was devoted to providing the social overhead infrastructure necessary for growth. This created stark inequalities within the Dakarois economy. Workers’ wages in Dakar often grew faster than agricultural incomes using standard methods of measurement; however, if housing costs are adequately accounted for then urban unskilled wages never outpaced rural incomes by much. The fruits of the groundnut boom accrued mainly to urban landlords, not workers. The unequal distribution of agricultural growth placed severe constraints on industrialisation. An import-substituting strategy was always a risky proposition, but the failure of the attempts at postcolonial federalism in West Africa definitively doomed it: the size of the domestic Senegalese market and the structure of demand for industrial output was unlikely to allow import-substituting industries to achieve competitive efficiency.