Rural electrification is closely linked one way or another to rural development, and enables the understanding of the complexity of social and economic development paths. The objective of this work is to analyse rural electrification in a European peripherical country like Spain throughout the twentieth century, contributing to the international debate on the issue. The article studies the territorial expansion of electricity in the Spanish countryside, tracing different phases and explaining the delay in the construction of a national network. It also analyses the relationship that arose in the long term between electrification and the evolution of the agricultural sector. The article concludes that, in the Spanish case, rural electrification played a modest role in agricultural change until the 1980s and was, to a great extent, the consequence, rather than the cause, of the modernisation of the sector to these years.