After completing his apprenticeship in September 1910, Broz used his contacts to gain employment in Zagreb and at the age of 18 joined the Metal Workers' Union and participated in his first labour protest.
Efter at være fuldt oplært i september 1910 gjorde Broz brug af sine kontakter til at få job i Zagreb, og i en alder af 18 år blev han medlem af Metalarbejdernes Fagforening og deltog i sin første demonstration.