Major League Baseball executives vote to hold a free-agent draft in New York City. A new TV pact is also signed.
Willie Mays‚ the highest-paid player in baseball‚ signs a $105‚000 contract with the Giants.
January 16 – American League owners vote 9–1 against Charlie Finley's Louisville moving proposal. Finley is given an ultimatum to sign a lease in Kansas City or lose his franchise.
January 28 – Cincinnati Reds center fielder Vada Pinson is cleared of assault charges stemming from a September 5‚ 1963‚ incident when Cincinnati sportswriter Earl Lawson does not pursue charges further.
January 29 – Pitcher-writer Jim Brosnan is given permission by the Chicago White Sox to make his own deal with another team. His in-season writing has been censured by Sox general manager Ed Short.
January 30 – The United States Senate Subcommittee on Monopolies begins hearings on baseball.
Finally, Charlie Finley gives in to American League pressure and signs a four-year lease with the municipal government to keep the Athletics in Kansas City. Finley wanted two years. His exasperated AL colleagues voted 9-1 that KC's offer was reasonable.
August 12 – Mickey Mantle hits a home run from both sides of the plate in a 7–3 Yankees win over the Chicago White Sox. It is the tenth time in his career that he has done so and a major league record for switch-hit homers in a game.
August 20 – At Comiskey Park, the Chicago White Sox complete a four-game sweep of the New York Yankees with a 5–0 shutout. As the Yankees' team bus heads to O'Hare International Airport after the game, infielder Phil Linz takes out a harmonica and plays a plaintive version of "Mary Had a Little Lamb." Manager Yogi Berra tells Linz to put the harmonica away. After Linz asks what Berra had said, Mickey Mantle tells Linz to "play it louder," which he does, prompting an unusually angry Berra to storm to the back to the bus and slap the harmonica out of Linz' hands; the instrument strikes Joe Pepitone's knee. The "Harmonica Incident" convinces the Yankee front office that Berra has lost control of the team and cannot command respect from his players. As a result, the decision is made to fire Berra at the end of the season.
September 27 – Johnny Callison hits three home runs, but the Phillies lose to the Milwaukee Braves 14–8. The Phils suffer the seventh loss in their 10-game losing streak, while the Reds sweep the New York Mets (4–1 and 3–1). These results knock Philadelphia out of first place, with the Reds replacing them atop the NL standings. The Phillies would never return to first place in 1964.
September 29 – The Pittsburgh Pirates blank the Reds 2–0 at Crosley Field (despite the Reds getting 11 hits off Bob Friend) to end the Reds' nine-game winning streak. Meanwhile, Ray Sadecki records his 20th victory as his St. Louis Cardinals defeat the Phillies 4–2 at Busch Stadium, the seventh win in the Cardinals' eight-game winning streak and the ninth loss in the Phillies' 10-game losing streak. The win puts the Cardinals into a tie for first place with the Reds; St. Louis had been 11 games out of first on August 23.
October 3 – As a result of the now-concluded Phillies' 10-game losing streak, this day begins with four teams still having a mathematical shot at the NL pennant, and it is still mathematically possible to get a 4-way tie for such. But then one of those four teams, the San Francisco Giants, is eliminated with a 10–7 loss to the Chicago Cubs. At the end of the day's play, the Reds and the Cardinals are tied for 1st place, with the Phillies a game back. In recent days, the NL has had to scramble to schedule various possible playoffs.
October 4 – The Phillies defeat the Reds, 10–0, in the last regular-season game for both teams unless there is a playoff; because of the Reds' loss, the Cardinals clinch a tie for the NL pennant. At the end of that game, the Phillies and Reds are 1/2 game back of the Cardinals, and await the result of the Cardinals-Mets game. Then, the Cardinals, never in first place until the last week of the season, clinch their first pennant since 1946 with an 11–5 win over the Mets, who had just beaten the Cardinals twice in the two preceding days. The win by the Cardinals averts a three-way tie for the NL pennant, with the Phillies and the Reds both finishing one game back in a second-place tie.
October 16 – The day after the final game of the World Series, the managerial posts of both pennant winning teams are vacant. In the morning, Johnny Keane, manager of the victorious St. Louis Cardinals, resigns, much to the surprise of owner Gussie Busch. Hours later, New York Yankee general manager Ralph Houk fires Yogi Berra as his manager, citing Berra's lack of control over team and his inability to command respect from his players. Less than a week later, Houk replaces Berra with Keane, who himself will be replaced by coach and former Cardinal star Red Schoendienst. Meanwhile, Berra reunites with Casey Stengel by becoming a coach with the New York Mets.
December 1 – The Houston Colt .45s officially change their nickname to Astros. The change coincides with the team's impending move from Colt Stadium to the Harris County Domed Stadium, also known as the Astrodome. A change in name for the three-year-old franchise is necessitated due to a dispute with the Colt firearm company; the Astros name is chosen due to Houston being the home of NASA's Manned Spacecraft Center (later the Lyndon B. Johnson Space Center).
February 4 – Fred Smith, 85, pitcher for the 1907 Cincinnati Reds.
February 12 – Al Pierotti, 68, pitcher for the Boston Braves from 1920–1921, who was also an offensive lineman in the American Professional Football League from 1920 through 1929.
February 14 – Bill Stewart, 69, National League umpire from 1933 to 1954 who worked four World Series, four All-Star Games and the 1951 NL pennant playoff; also a hockey coach and referee who led the Chicago Black Hawks to the 1938 Stanley Cup title.
February 15 – Ken Hubbs, 22, second baseman for the Chicago Cubs and the 1962 Rookie of the Year, in a plane crash.
February 15 – Fred Trautman, 71, pitcher for the 1915 Newark Peppers of the Federal League.
February 22 – Ike Samuels, 90, third baseman for the 1895 St. Louis Browns of the National League.
February 24 – Henry Baldwin, 69, backup infielder for the 1927 Philadelphia Phillies.
February 27 – Tony Smith, 79, shortstop for the AL Washington Senators (1907) and the NL Brooklyn Superbas/Dodgers (1910–1911).
September 11 – Tom Meany, 60, sportswriter for six New York newspapers, as well as Collier's magazine from 1923 to 1956; also publicity and promotions director for the New York Mets since their 1961 formation.
September 26 – Paul Zahniser, 68, pitcher for the Washington Senators, Boston Red Sox, and Cincinnati Reds from 1923 to 1929.
September 27 – Jud McLaughlin, 52, pitcher for the Boston Red Sox between 1931 and 1933.