Jews began to settle in Ostrołęka in the last decade of the eighteenth century. In 1794, a plot of land was selected for a Jewish cemetery and a synagogue was built around the same time. One of the first rabbis was named Izaak.
In 1812, Ostrołęka’s Jewish population comprised 14 families whose members engaged in the following businesses: 4 shopkeepers, 3 innkeepers, 3 butchers, a watchmaker, a hatter, a circumciser and a teacher. Jews lived in the market square vicinity. In 1824, their number grew to 73. They lived in six houses, three were of which were by the market square while the rest were on a street leading to it. The remaining Jews rented houses in different parts of the town.
In 1826, the boundaries of the Jewish Quarter, which encompassed the Horse Market, was bounded by Cygańska St., Magazynowa St., Różańska St., Solna St., Piaski St., Folwarczna St. and Tylna St. Two families were allowed to live outside the area provided they built a brick house.
The craft village located at the outskirts of the town accelerated the development of the Jewish settlement. Jews began to set up larger craft workshops for processing amber, milling and spinning. Spinning pioneers included the Bondi family of Austrian origin, which established a cotton mill in 1829. In 1832, it expanded and provided employment for 20 people. The company's products received awards at fairs in 1839 and 1842. A sizable group of Jews found employment in farming, tar production, and amber processing. Others were involved in traditional crafts (glaziery, butchery, shoemaking, tailoring, etc), inn keeping, leasing of local taxes and trade.
During the 1830-31 uprising, Ostrołęka was partly destroyed and the synagogue was burned. Services were then conducted in a wooden house on Rożańska Street, the condition and location of which left much to be desired. In 1832, Mordka Fiszel Shapira made efforts to take over the position of rabbi.
In the later 1840s, the rabbi or, more likely, the assistant rabbi in Ostrołęka was someone named Izaak. In the same period, construction of a synagogue was initiated. Proposals to get the government to support the building made in 1841-1842 and in 1848 failed. The construction started only thanks to an interest-free loan for 1500 rubles given by Chaim Tykociner. The synagogue was completed in 1856.
In 1862, the Jewish quarter was formally abolished. During this period, the Jewish community was headed by Rabbi Jechiel Mechel Goldszlak, who was a well known Talmudic scholar and author of several religious works.
In the second half of the nineteenth century, a significant number of Jews engaged in large scale trade with Russia appeared, mainly trading in grain, salt, wine, iron, leather and kerosene. Others traded both legal and contraband goods on a smaller scale with Prussia. Many Jewish suppliers were engaged in the lucrative business of supplying numerous military units stationed in the province of Łomża. The construction of railway lines connecting Ostrołęka with Małkinia, Łapy and Tłuszcz in the late nineteenth century enervated the local economy. Over time, 30 Jewish families, including shopkeepers, two windmill owners, carters, several craftsmen, a rabbi and a circumciser owned homes on the road leading from the town to the train station (6 km from the center). The remaining Jewish residents of Ostrołęka lived primarily around the market (on side streets between the market and the market square), present day Kilińskiego and Ostrowska streets, and by the milk market.
In 1892, 112 Jewish craftsmen were working in the town: 29 shoemakers, 25 tailors, 12 carpenters, 10 saddlers, 8 blacksmiths, 5 coachmen, 5 tinkers and locksmiths, 4 hatters, 2 dyers, 2 watchmakers as well as butchers, bakers, carters and labourers; the total number of craftsmen in the town was 185.
Religious life revolved around the synagogue and the bet ha-midrash. Their activities were complemented by a variety of educational, religious and charitable institutions, including cheders, Talmud Torah, a yeshiva, the Linas ha-Tzedek brotherhood and the Chevra Kadisha brotherhood. Several notable characters appeared along with the development of the community. The Orthodox Jews were a strong group in religious life. In addition to supporters of traditional Judaism, the Hasidim from Góra Kalwaria, Warka, Aleksandrów and Mszczonów had a lot of influence. Among the rabbis was the well-known rabbi from the Hasidim in Góra Kalwaria – Josele Harif. Along with him, in the late nineteenth century, was the tzaddik Jechoszua, who became a famous teacher and author of several religious works. Another tzaddik from Ostrołęka was Salomon Jeremiasz Grinberg, known as Rabbi Shlomo. In 1899-1902, Mosze Nachum Jaruzolimski served as the town rabbi. After leaving Ostrołęka he occupied the same position in Kielce. In 1904, Jakub Szlomo Fajzman became the rabbi. A year later, he was succeeded by Icchak Burnsztejn, who held the office until the outbreak of WWII.
At the end of the nineteenth century, the first supporters of Zionism and socialism started to appear.
After the outbreak of the First World War, the Russians expelled the Jews living on the right bank of the Narew River. After the occupation of the city by the Germans in August 1915, the Jews were expelled again in a matter of a few hours and ended up in Łomża. Jews began to return gradually to Ostrołęka in the autumn of 1915. In 1916, the Jewish community numbered 4,110 people out of a total population of 4,907 in Ostrołęka. Even during the war, members of the community began reconstructing Ostrołęka. Most of them lived in the southeastern part of the town. A synagogue, yeshiva and prayer house were built and the Assistance Committee helped the poor. After the war, a number of Jewish political parties and a variety of organisations were established[1.1]
The beginning of the German occupation on 10 September 1939 brought the first waves of repression and persecution. At the end of September 1939, the synagogue was set on fire. In early October 1939, the Jews were given two hours to leave Ostrołęka. After entreatments were made, the execution of command was postponed for two days. Those expelled were only allowed to take hand luggage. Their remaining property had to be left intact. German soldiers watched as the Jews were guided in the direction of Łomża, which after September 17 was occupied by Russian troops. However, some headed for other towns. Those who returned to Ostrołęka were shot[1.2].
Many of the Jews expelled from Ostrołęka later met the same tragic fate as the vast majority of Polish Jews at Treblinka and other death camps. A few of them, however, managed to survive the occupation and settle either in Israel or in various other countries around the world[1.3].