The Expos joined the National League in 1969, along with the San Diego Padres. Their home stadium was Jarry Park, in Montreal. The Expos suffered through 10 straight losing seasons under their first manager, Gene Mauch (1969-1975) and three other managers. In 1979 they posted their first winning record with a 95-65 record, under manager Dick Williams. They would post five consecutive winning seasons, including their only division championship, in the split season of 1981. They defeated the Philadelphia Phillies 3-2 in the divisional series, but lost to the Los Angeles Dodgers 3-2 in the National League Championship Series. Montreal was led through these years by a core group of young players, including catcher Gary Carter, outfielders Tim Raines and Andre Dawson, third baseman Larry Parrish and pitchers Steve Rogers and Bill Gullickson. The Expos had several mediocre years in the mid 1980s under manager Buck Rodgers, but rebuilt and under manager Felipe Alou, who took the position midway through the 1992 season, finished second in the National League East in both 1992 and 1993. 1994 proved to be heart-breaking for the Expos. With a very talented group of players, including outfielders Larry Walker, Moises Alou and Marquis Grissom, second baseman Delino DeShields and pitchers Ken Hill, John Wetteland and a young Pedro Martinez, the Expos had the best record in major league baseball, 74-40 when the strike forced the end of the season.

The Expos lost most of their star players through free agency and trades, and have posted losing records since 1994, except for a second place finish in 1996.

Montreal is often cited as an example of a small-market team, unable to compete with teams in bigger markets such as New York, Chicago and Los Angeles. Jeffrey Loria, the new owner, made some personnel moves, however the future of the franchise in Montreal does not look very strong. Attendance in the 2001 season was usually fewer than 10,000 people. On November 7, 2001, Commissioner of Baseball Bud Selig announced that major league baseball would undergo a contraction of two teams, after a 28-2 vote by the owners. Montreal was one of the dissenting franchises.

On February 14, 2002, after a 30-0 vote, Major League Baseball formed a Delaware partnership (Expos Baseball, LP) to buy the Expos for US $120,000,000 with the intent of eliminating the franchise along with the Minnesota Twins. Following legal maneuvers that prevented the Twins from being shuttered, followed by a collective bargaining agreement between MLB and its players association which prohibited "contraction" through 2006, the team survived. Major League Baseball named Frank Robinson manager and Omar Minaya as vice-president and general manager.

In 2003, the team played 22 of its home games at Hiram Bithorn Stadium in San Juan, Puerto Rico, despite having the highest percentage attendance increase in 2002 to go with a second place finish in the National League East. Despite being a considerably smaller facility (it seats approximately 19,000) than Montreal's Olympic Stadium, Bithorn regularly outdrew the attendance in Montreal. Thanks in large part to the San Juan games, the Expos were able to draw over a million fans at home in 2003, for the first time since 1998.

The players' union initially rejected continuing that arrangement for the 2004 season, but later relented. It is widely expected that in 2005 or shortly after, the team will move to another city. San Juan, Monterrey, Mexico, Portland, Oregon, Washington, DC, Northern Virginia, and Norfolk, Virginia have all been proposed as new homes for the team. Selig later added Las Vegas to the list of potential Expos homes. There is currently a lawsuit underway by the former team owners against Major League Baseball and the former majority owner, Jeffrey Loria.

--Wikipedia