Ya'ari was one of the founders of Bitania, the first collective settlement of Hashomer Hatzair.
He was among the founders of the Histadrut workers' syndicate.
Since 1924 he served as Secretary of the world Hashomer Hatzair.

In 1927, he founded Kibbutz Artzi, was elected its secretary and took part in drafting its principles.
In 1929, he was among the founders of kibbutz Merhavia, where he lived until he died.
Ya'ari was one of the founders of Bitania, the first collective settlement of Hashomer Hatzair. He was among the founders of the Histadrut workers' syndicate. Since 1924 he served as Secretary of the world Hashomer Hatzair.
In 1927, he founded Kibbutz Artzi, was elected its secretary and took part in drafting its principles. In 1929, he was among the founders of kibbutz Merhavia, where he lived until he died.
Meir Ya'ari