Tolland County is a county located in a northeastern part of Connecticut. As of 2010, the population was 152,691. Tolland County is incorporated into thirteen towns and was originally formed on 13 October 1785 from western Windham County, Connecticut.
Counties in Connecticut have no governmental function: all legal power is vested in the state, city, and town governments. The office of High Sheriff in Connecticut counties was officially abolished by ballot in 2000, and corrections and court service were transferred to the state marshalls. Tolland County has the same boundaries as the Tolland Judicial District.
According to the 2000 census, the county has a total area of , the smallest county in Connecticut, of which (or 98.34%) is land and (or 1.66%) is water.
Part of the county is part of the Hartford metropolitan area and part is part of the Springfield, Massachusetts, metropolitan area. The county contains the University of Connecticut in the community of Storrs within the town of Mansfield.
The FIPS code for Tolland County is 009013.