It has the oldest University in the country, and, until the formation of the United Principalities, it was the capital of Moldavia.

According to the 1930 census data, the county population was 275,796 inhabitants, 81.6% Romanians, 14.6% Jews, 0.6% Russians, 0.5% Hungarians, 0.4% Germans, as well as other minorities.

[11] From the religious point of view, the population was 82.0% Eastern Orthodox, 14.9% Jewish, 2.3% Roman Catholic, as well as other minorities.

In 1930, the county's urban population was 107,804 inhabitants, 102,872 in Iaşi and 4,932 in Târgu Frumos, comprising 60.8% Romanians, 33.6% Jews, 0.9% Germans, 0.9% Russians, as well as other minorities.

[11] From the religious point of view, the urban population was composed of Eastern Orthodox (61.4%), Jewish (34.4%), Roman Catholic (3.0%), as well as other minorities.