IUC) is the Cantabrian federation of the Spanish left wing political and social movement United Left.

Jorge Crespo is the current General Coordinator.

The Communist Party of Cantabria (PCC-PCE, Cantabrian federation of the PCE) and Izquierda Abierta.

In the Cantabrian elections of 2011 IUC made a coalition with Izquierda Anticapitalista with the name Social and Ecologist Left.

This article about an organisation based in Spain is a stub.