Since Ukrainians in Poland had only limited control over the formal education of their children, the Plast scouting movement took up the challenge of inculcating youth with a Ukrainian national identity. Plast scouts came into being on the eve of World War I on Ukrainian lands in both the Russian and the Austro-Hungarian empires, but it was during the interwar years in western Ukraine (in particular Galicia and Transcarpathia) that they had their greatest success. By 1930, the organization had over 6,000 male and female members in branches affiliated with secondary schools in Galicia and with Prosvita societies in western Volhynia. Concerned by Plast's general popularity and the fact that many of its 'graduates' after age eighteen joined clandestine Ukrainian nationalist organizations, Poland's authorities increased restrictions on the movement until banning it entirely after 1930. It nonetheless continued to operate underground or through other organizations for the rest of the decade.