A member of the Hibbat Zion movement from its inception, Reines joined Rabbi Samuel Mohilever in proposing settlement which combined Torah study with physical labor. He was also one of the first rabbis to answer Herzl's call to become part of the Zionist movement; as such, he attended the First Zionist Congress (Basle, 1897). Herzl recognized the need for rabbis to support his new movement.
While most of his eastern and western European rabbinical colleagues remained opposed to political Zionism, in 1902 Reines published a book, Or Hadash al Tzion (A New Light on Zion) which countered the claims of the Anti-Zionist rabbis. The same year he organized a conference of the religious Zionist movement in Vilna, where the Mizrachi movement was founded. He was recognized as the movement's leader at its founding convention in Pressburg, Bratislava in 1904.
In 1905, Reines accomplished his own personal dream with the establishment of a yeshiva in Lida where both secular and religious subjects were taught. In sharp contrast to the pilpul method which characterized eastern European Jewish scholarship, Reines's approach was most unusual for the time.