After the Nazi invasion, many Zionist Youth leaders - along with tens of thousands of Jews - fled Poland to Russia, or independent Lithuania. Some intended to reach Palestine- but they suddenly realised that they had abandoned their young students (chanichim). Many felt very guilty at this and actually smuggled themselves back into the Ghetto to look after their chanichim. Mordechai Anielewicz, the future leader of underground, was amongst those who fled and then returned to take part in armed resistance.

Once in Warsaw, the first task was to find chanichim and open Movement branches, often in private homes. In these turbulent times the Movements even more filled the role of a replacement family or school as traditional family life was collapsing all around. In the early months, activities were very boisterous as they had been before the, war, and included singing in the streets. Numbers are difficult to establish but Dror Hechalutz had 300 chanichim in Warsaw, Hashomer Hatzair had 800, Hanoar Hatzioni had 160 and one of Betar's eight Warsaw groups had 80 chanichim. The Warsaw Movement leaders also took on coordinating Movement activities throughout Poland.

All the movements were concerned with welfare, such as setting up and supplying soup kitchens and arranging meals for hungry members. They also continued with educational work, training, teaching and preparing chanichim for life in Israel. There were schools, libraries, a choir, as well as other activities that catered for educational and social needs. They also managed to reestablish training farms in cases where the Polish farmers needed extra labour. This was done with German permission, but the Nazis did not know the nature of these young Jews. Two of the farms were used by Betar and one by Hashomer Hazair. These youngsters would later take part in the armed resistance against the Germans.