In 1913 he took part in the founding of Ahuza Alef in New York, an organization dedicated to the purchase of lands and the establishment of a Hebrew settlement, to be inhabited by Jews tilling their own soil.

While in the United States, Ostrovsky earned his living teaching a wide variety of subjects, including Hebrew, history, Bible, as well as Yiddish.

Contemporaneously with his educational work, Ostrovsky was active in the Zionist Movement's labor organization, Poale Zion, with the leaders David Ben-Gurion, Ber Borochov and Yitzhak Ben-Zvi.

In 1930 Ostrovsky finally succeeded in fulfilling his Zionist ambition by giving up his comfortable existence in the USA and settling in Ra'anana, a small town in the Sharon plain, with his wife and two children.

His modest mode of life, scorning all forms of luxury and excess, placed him on equal ground with the hard working and low earning inhabitants of his town.

He set high standards for the city as a 'green' settlement, promoted equality and the welfare of citizens, and laid the foundation stones of many public and educational institutions.