This article deals with social and community work undertaken by the clergy of the Diocese of Łomża in the period 1918-1939. Although their initiatives reached out in many directions, priority was given to workers’ and peasants’ organizations, cultural life, education, local government, and charity. Calls for expanding the Church’s social work came from both the diocesan authorities and local priests. Social work amid the working class was focused on the Association of Christian Workers (SRCh), an organization launched on the initiative of the clergy in Augustów in 1906. Apart from its educational and religious programs, SRCh sought to involve its members in various co-op projects. The clergy played an important role in the creation of local Agricultural Societies and popularizing co-op shops, co-op savings and lending banks, etc. These initiatives had a marked impact on rural development in the Kurpie region. With so much emphasis put on education, it was not long before new, specialized institutions sprang from the ground. They were the Institute of Religious Culture, the Popular University at Łomża, the Trades School at Rybaki, and local branches of the Polish Educational Society Macierz Szkolna, Polish Scouting Association (ZHP), and Akcja Katolicka. Especially Akcja Katolicka was remarkably successful in organizing pilgrimages, Lenten teachings, reunions, courses, lectures, legal advice services, concerts, holiday camps for children, as well as setting up lecture-rooms, libraries, parish, and community halls, etc. Members of the clergy took part in the work of the local government, usually at the level of municipal and district councils. Among the clerical public office holders was Father S. Szczęsnowicz. As a member of the First Legislative Sejm, he played an important part in Poland’s efforts to secure the withdrawal of German troops from the Suwałki region and the speedy endorsement by the Entente of a demarcation line in the northeast (the so-called Foch Line). Charity was always a top priority with the clergy of the Łomża diocese. They organized their own Charitable Society, assisted the work of St. Vincent de Paul Conferences and Societies, and joined current campaigns such as helping immigrants from Russia, sending aid to the flood victims in Małopolska in 1927, or assisting the unemployed during the economic crisis of the 1930s.