"[2][3] He is best known for his theoretical work on the state, but he also offered Marxist contributions to the analysis of fascism, social class in the contemporary world, and the collapse of dictatorships in Southern Europe in the 1970s, such as Francisco Franco's rule in Spain, António de Oliveira Salazar's in Portugal, and Georgios Papadopoulos' in Greece.

Borrowing from Antonio Gramsci's notion of cultural hegemony, Poulantzas argued that repressing movements of the oppressed is not the sole function of the state.

In his later works, Poulantzas analysed the role of what he termed the "new petty bourgeoisie" in both consolidating the ruling classes hegemony and undermining the proletariat's ability to organise itself.

The fragmentation (some would argue the demise) of the class system is, for Poulantzas, a defining characteristic of late capitalism, and any politically useful analysis must tackle this new constellation of interests and power.

This was necessary for the continued existence of capitalism, for if the ruling class had simply repressed the movements and avoided making any concessions, it could have led to a socialist revolution.

In many areas, he foresaw the current debate on the critical Marxian language of class, bourgeoisie, and hegemony finds little echo in contemporary political science, where its positivism requires researchers to focus on putative measurable and objective entities.