Its session laws are generally adopted by majority vote in both houses, and upon gaining the assent of the Governor of Illinois.

Future U.S. President Abraham Lincoln successfully campaigned as a member of the Whig Party to serve in the General Assembly in 1834.

[3] He served four successive terms 1834–42 in the Illinois House of Representatives, supporting expanded suffrage and economic development.

Due to the unwillingness of downstate Illinois to cede power to the growing Chicago area, the district boundaries were not redrawn from 1901 to 1955.

This ensures that Senate elections reflect changes made when the General Assembly is redistricted following each United States Census.

To prevent complete turnovers in membership (except after an intervening Census), not all Senators are elected simultaneously.

The Illinois Secretary of State convenes and supervises the opening House session and leadership vote.

[14] The General Assembly's first official working day is the second Wednesday of January each year.

[15] Members of the General Assembly may not hold other public offices or receive appointments by the governor, and their salaries may not be increased during their tenure.

[15] Seats in the General Assembly may become vacant due to a member resigning, dying, being expelled, or being appointed to another office.

[20] The General Assembly can override full, amendatory and item vetoes by a three-fifths majority vote in both chambers.

[23] This power is currently exercised by the Joint Committee on Administrative Rules (JCAR).

[26] The General assembly gave it the power to temporarily block or suspend administrative regulations for 180 days in 1980.

[26] In September 2004, the General Assembly expanded this temporary suspension power into a permanent veto.

[28] Among the charges brought against Governor Rod Blagojevich in his 2009 impeachment trial was that he had not respected the legitimacy of JCAR blocking his rulemaking on healthcare in 2008.