The central feature which has emerged from this study is that from its foundation in 1879, the PSOE was always marked by a profound ideological ambiguity. This ambiguity centred on the nature of the relationship between Socialism and democracy. Essentially, the PSOE Marxists never worked out clearly either the aims or the methods of their struggle. Most critically, the concept of revolution was never formally elaborated; instead, it was referred to in only the most unspecific terms as the inevitable precursor to an equally inevitable Socialist future. This left the PSOE operating within a vague hinterland between a grudging gradualist, parliamentary legalism and occasional essays at a revolutionary overthrow of the state, most notably in 1917 and 1934. Neither approach was founded upon a coherently developed Marxist analysis of the socio-political and economic situation in Spain at any given moment. Thus it was that there emerged such a consistent pattern of division and failure within the PSOE. Indeed, the ‘radicalisation’ of the PSOE during the Republic, far from representing a new phase within the development of the party, actually represented a logical culmination of tensions which had always existed within its heart.

In part, the PSOE's ideological ambiguity reflected divisions over the aims, goal and methods of revolution which are immanent to Marxism itself, and which retain their significance even today. The debates over ‘Eurocommunism’ in the 1970s and 1980s can be seen as simply the latest in a long line of attempts to confront the question of the relationship between parliamentary democracy and Socialism.