Online:

1. YIVO Encyclopedia of Jews in Eastern Europe – a full-text encyclopedia with many images, maps, videos, and more. Worth spending many hours with! 
2. YIVO Digital Archive on Jewish Life in Poland: “Explore this world through manuscripts, posters, photographs, music and other artifacts.”
3. JewishGen.org – the ultimate resources for the Jewish genealogist. Includes, among many other sections:
   – Town finder
   – Yizkor Book Project (yizkor books are memorial volumes dedicated to a particular shtetl published in the post-Holocaust period)
4. Virtual Shtetl – Polish site (with English version) with much information (and more added all the time) about Jewish history and sites in Poland

Print
General

1. Israel Bartal, The Jews of Eastern Europe, 1772-1881. A very readable short textbook by one of the leading Israeli scholars of East European Jewry.
2. Zvi Gitelman, A Century of Ambivalence: The Jews of Russia and the Soviet Union, 1881 to the Present. Originally written to accompany a YIVO exhibit, this readable book by an eminent scholar of Russian and Soviet Jewry is lavishly illustrated with photographs
3. Eva Hoffman, Shtetl: The Life and Death of a Small Town and the World of Polish Jews. An exploration of Jewish life and Jewish-Christian relations over many centuries in one small Polish town
4. Gershon Hundert, Jews in Poland-Lithuania in the Eighteenth Century: A Genealogy of Modernity. A scholarly but accessible history of the Jews of premodern Poland.
5. Ezra Mendelsohn, The Jews of East Central Europe between the World Wars. A survey and comparison of Jewish life in seven countries (including Poland, Hungary, and Czechoslovakia) in the 1920s and 1930s.
6. Yohanan Petrovsky-Shtern, The Golden Age Shtetl: A New History of Jewish Life in East Europe. Based almost entirely on documents from former Soviet archives, this engaging book attempts to deconstruct a number of myths about the shtetl in its “golden age” (1790s-1840s).  
7. Antony Polonsky, The Jews in Poland and Russia: A Short History. A scholarly but very readable survey published only a few years ago, by one of the leading scholars of East European Jewish history in the Anglophone world. Condensed from the full three-volume work.
8. Byron L. Sherwin, Sparks Amidst the Ashes: The Spiritual Legacy of Polish Jewry. A collection of essays by a noted scholar of Jewish philosophy and mysticism that delve into the spiritual and religious creativity of Polish Jews over the centuries. Argues that ”the spiritual heritage of Polish Jewry can provide a foundation for an authentic Jewish continuity.”

Memoirs and Documents

1. Hirsz Abramowicz, Profiles of a Lost World: Memoirs of East European Jewish Life Before World War II. Published in Yiddish in 1958, a combination of memoir and sociological essay. Focuses on Lithuania.
2. Awakening Lives: Autobiographies of Jewish Youth in Poland before the Holocaust, ed. Jeffrey Shandler.
3. Lucy Dawidowicz, From That Place and Time: A Memoir, 1938-1947. Covers the year that this American-Jewish historian spent in Vilna just before World War II and her return to Vilna after the war.
4. Everyday Jewish Life in Imperial Russia, ed. ChaeRan Y. Freeze and Jay M. Harris (2013). A vast collection of documents on many aspects of Jewish life, including religious practice, marriage and sexuality, and Jewish-Christian relations. 
5. Ben-Zion Gold, The Life of Jews in Poland before the Holocaust: A Memoir.
6. The Golden Tradition: Jewish Life and Thought in Eastern Europe, ed. L. Dawidowicz. A collection of documentary sources from original Yiddish, Hebrew, Russian, and Polish texts, graced with a comprehensive introduction to Jewish life in Eastern Europe
7. Chaim Grade, My Mother’s Sabbath Days. The great Yiddish writer’s memories of life in interwar Vilna, as well as of his refugee years in wartime Soviet Union and his subsequent return to a destroyed Vilna. Riveting and poignant.
8. Puah Rakovsky, My Life as a Radical Jewish Woman: Memoirs of a Zionist Feminist in Poland, trans. Harshav, ed. Paula Hyman. The amazing life story of a pioneering Jewish woman who lived through almost a century (1865–1955) of Jewish history in Russia, Poland, and Eretz Israel.
9. Isaac Bashevis Singer, In My Father’s Court. Memoir of a Jewish childhood in Warsaw just before, during, and after World War I.
10. Pauline Wengeroff, Memoirs of a Grandmother: Scenes from the Cultural History of the Jews of Russia in the Nineteenth Century (2 vols.), trans. and ann. Shulamit Magnus. Gripping memoir of a Jewish woman who was witness to a century of Jewish life and transformation in the Russian Empire, including fascinating descriptions of traditional Jewish folkways. With an insightful introduction and copious notes by Magnus.