The Seventy-Eighth Wisconsin Legislature convened from January 11, 1967, to January 6, 1969, in regular session.^[1]

This session saw the culmination of Governor Warren P. Knowles state government reorganization and modernization plan, including the passage of the signature government reorganization law, which consolidated 85 executive branch agencies into 32 executive departments, and the passage of twelve amendments to the state constitution (the most in any single legislative session).

Senators representing odd-numbered districts were newly elected for this session and were serving the first two years of a four-year term. Assembly members were elected to a two-year term. Assembly members and odd-numbered senators were elected in the general election of November 8, 1966. Senators representing even-numbered districts were serving the third and fourth year of a four-year term, having been elected in the general election of November 3, 1964.^[1]

• January 2, 1967: Second inauguration of Warren P. Knowles as Governor of Wisconsin.
• January 15, 1967: The Green Bay Packers won Super Bowl I.
• January 27, 1967: An accidental fire destroyed Apollo 1 during a launch rehearsal at Cape Canaveral, killing all three astronauts assigned to the mission.
• February 10, 1967: The Twenty-fifth Amendment to the United States Constitution came into force when a sufficient number of states ratified.
• March 4, 1967: Wisconsin Supreme Court justice Myron L. Gordon resigned after he was confirmed as a United States district judge for the Eastern District of Wisconsin.
• March 13, 1967: Wisconsin governor Warren P. Knowles appointed county judge Connor Hansen to the Wisconsin Supreme Court, to succeed Myron L. Gordon.
• April 4, 1967: 1967 Wisconsin Spring election:
  • Robert W. Hansen was elected to the Wisconsin Supreme Court, defeating incumbent chief justice George R. Currie. He was the only Wisconsin chief justice ever defeated seeking re-election.
  • Wisconsin voters ratified eight amendments to the state constitution:
    • Combining the election of governor and lieutenant governor into a single ticket election rather than two separate elections.
    • Doubling the term of the governor and lieutenant governor to four years from two.
    • Doubling the term of the secretary of state to four years from two.
    • Doubling the term of the attorney general to four years from two.
    • Doubling the term of the state treasurer to four years from two.
    • Abolishing term limits for sheriffs.
    • Adding section 23 to Article I of the constitution, establishing that the prohibition on sectarian instruction in public education should not prevent state entities from paying for transportation for children to attend private schools.
    • Allowing for judicial salary increases to take effect during the immediate term, rather than waiting until after the next election.
• July 30, 1967: A fight between teenagers in Milwaukee escalated into the 1967 Milwaukee riot—one of 159 race riots which swept the country in the long, hot summer of 1967.
• August 30, 1967: The United States Senate confirmed Thurgood Marshall as an associate justice of the United States Supreme Court, making him the first African American to serve on the court.
• October 18, 1967: A student anti-war protest on the campus of the University of Wisconsin–Madison devolved into a riot, injuring 76 people.
• December 31, 1967: The Green Bay Packers defeated the Dallas Cowboys in the 1967 NFL Championship Game. The game was referred to as "the Ice Bowl" due to the game-time temperature of −15 °F (−36 °F wind chill).
• January 1, 1968: E. Harold Hallows became the 20th chief justice of the Wisconsin Supreme Court by rule of seniority, at the expiration of the term of chief justice George R. Currie.
• January 14, 1968: The Green Bay Packers won Super Bowl II.
• March 31, 1968: U.S. president Lyndon B. Johnson announced, during a speech about the status of the Vietnam War, that he would not run for another term as president.
• April 2, 1968: 1968 Wisconsin Spring election:
  • Wisconsin voters ratified four amendments to the state constitution:
    • Allowing the legislature to hold more than one session per biennium.
    • Allowing the legislature to set a uniform retirement age for state judges.
    • Clarifying that a judge may serve in a temporary role by appointment beyond the retirement age.
    • Allowing for appropriations for forestry improvements from funding sources other than a property tax.
• April 4, 1968: Martin Luther King Jr. was assassinated in Memphis, Tennessee.
• June 6, 1968: Democratic presidential candidate Robert F. Kennedy was assassinated in Los Angeles, California.
• November 5, 1968: 1968 United States general election:
  • Richard Nixon (R) elected President of the United States.
  • Warren P. Knowles (R) re-elected to a third term as Governor of Wisconsin.
  • Gaylord Nelson (D) re-elected United States senator from Wisconsin.

• July 19, 1967: An Act to provide for the functional reorganization of the executive branch of Wisconsin state government by the orderly transfer of all functions now assigned by law to the 91 separate departments of the executive branch into a streamlined new structure of constitutional offices, operating departments, and independent institutions and agencies, and to make appropriations, 1967 Act 75. This was the signature legislative package of the major executive branch reorganization, championed by governor Warren P. Knowles. It reorganized the state executive branch into 32 executive agencies, down from 85 (or 91 by some measures).

• Regular session: January 11, 1967 – January 6, 1969