He was active in Polish cultural and pro-independence organizations. In 1905, while in high school, he joined such an organization and became the leader of one of its sections. In 1910 he founded his own organization, "Związek Młodzieży Postępowo-Niepodległościowej" (Youth Association for Progress and Independence). In 1915 he joined the Polish Military Organization ("Polska Organizacja Wojskowa", or "POW"), a precursor of Polish intelligence, and soon became "POW" deputy commander in Kiev. Arrested by authorities, he was freed right after the February 1917 Revolution. Soon Henryk Józewski returned to Kiev and resumed his activities with the "POW" once again.