The 1st Parliament of Ontario was in session from September 3, 1867, until February 25, 1871, just prior to the 1871 general election.

The 1867 general election produced a virtual tie between the Conservative Party led by John Sandfield Macdonald and the Liberal Party led informally by Archibald McKellar.

Macdonald ended up securing the Premiership by leading a coalition government with the support of moderate Liberals.

His Cabinet, nicknamed the Patent Combination, included two conservatives (John Carling and Matthew Crooks Cameron), a coalition Grit (Edmund Burke Wood) and two old school Baldwinite Reformers (Sandfield Macdonald himself and Stephen Richards).

In the first several years of Confederation, individuals could be elected to both federal and provincial parliaments and serve as MPs and MPPs at the same time.