The 100th New York State Legislature, consisting of the New York State Senate and the New York State Assembly, met from January 2 to May 24, 1877, during the first year of Lucius Robinson's governorship, in Albany.

Under the provisions of the New York Constitution of 1846, 32 Senators and 128 assemblymen were elected in single-seat districts; senators for a two-year term, assemblymen for a one-year term. The senatorial districts were made up of entire counties, except New York County (five districts) and Kings County (two districts). The Assembly districts were made up of entire towns, or city wards,^[1] forming a contiguous area, all within the same county.

At this time there were two major political parties: the Republican Party and the Democratic Party. The Prohibition Party and the Greenback Party also nominated tickets.

The New York state election, 1876 was held on November 7. The Democratic incumbent State Comptroller Lucius Robinson was elected Governor, and his running mate William Dorsheimer was re-elected Lieutenant Governor. The other three statewide elective offices up for election were also carried by the Democrats. The approximate party strength at this election, as expressed by the vote for Governor, was: Democratic 520,000; Republican 489,000; Prohibition 3,400; and Greenback 1,400.

The Legislature met for the regular session at the Old State Capitol in Albany on January 2, 1877; and adjourned on May 24.

George B. Sloan (R) was elected Speaker with 69 votes against 57 for Luke F. Cozans (D).

On April 3, the Legislature re-elected Superintendent of Public Instruction Neil Gilmour to a term of three years.^[2]

The Senate met for a special session at Saratoga Springs and adjourned on August 18.

On August 17, Superintendent of the New York State Banking Department DeWitt C. Ellis was removed from office.^[3]