1878 Major League Baseball season
| 1878 MLB season | |
|---|---|
| League | National League (NL) |
| Sport | Baseball |
| Duration | May 1 – September 30, 1878 |
| Number of games | 60 |
| Number of teams | 6 |
| Pennant winner | |
| NL champions | Boston Red Caps |
| NL runners-up | Cincinnati Reds |
The 1878 major league baseball season was contested from May 1 through September 30, 1878, and saw the Boston Red Caps as the pennant winner of the third season of the National League. There was no postseason.
Over the off-season, in December 1877, two teams would fold: Brooklyn Hartfords and St. Louis Brown Stockings. They were replaced by the Indianapolis Blues and Milwaukee Grays. Later in the offseason, the Providence Grays would join on February 6, raising the number of teams to seven. On April 1 or 2, the Louisville Grays would officially resign from the league, once again lowering the number of teams to six.