From the APDA website
Parliamentary debate is an off-topic, extemporaneous form of competitive debate which stresses rigorous argumentation, logical analysis, quick thinking, breadth of knowledge, and rhetorical ability over preparation of evidence. It is patterned after the style of platform debate first made famous at Oxford University.
The format pits two two-person teams against each other in a contest of argument, wit and rhetoric which roughly simulates debate in a House of Parliament. The Government (proposing) team prepares and presents a case for debate based on a topic or resolution announced only 15 minutes before the beginning of the round. The Opposition attempts to rebut the Government's proposal through counter-argument and refutation. The use of recorded evidence during the debate round is prohibited.
A different resolution is debated in every parliamentary debate round. Resolutions are chosen from a wide variety of political, philosophical, economic, cultural and humorous topics, and debaters often have a broad scope in which to define the specific case for debate which is drawn from the resolution. Hundreds of colleges and universities in the United States, Canada, Great Britain, and over thirty other nations participate in parliamentary debate. It is the fastest-growing form of intercollegiate debate in the world.
The Value of Parliamentary Debate
Parliamentary debate on APDA focuses on skills which are not greatly emphasized by other forms of intercollegiate debate. Rather than concentrating on extensive preparation of evidence, APDA encourages a breadth, as well as a depth, of knowledge -- as students can be forced to debate almost any topic at short notice, they must have a working knowledge of all manner of political, economic, social and philosophical issues. A high premium is placed on quick thinking and logical, rigorous analysis.
APDA debate is audience-centered; speaking skills learned on APDA can be directly appreciated by the general public, not only specially-trained judges. By focusing on argumentation and rhetoric rather than rapid recitation of evidence and technical rule-based strategies, parliamentary debate is an activity which is easily learned, extremely adaptable, and widely accessible, yet still rigorous, intellectually demanding, and rewarding.
The legacy of parliamentary debate can clearly be seen in the resumes of APDA alumni. In the past few years, APDA graduating classes have included several Rhodes, Marshall and Truman scholars, with numerous other alums attending top-rate graduate institutions like Harvard, Yale and Stanford Law Schools, Yale Medical School, and Princeton's Woodrow Wilson School.
The heart of APDA debate can be found in the organization's weekly tournaments. Ranging in size from 20 teams to over 160 teams, these two-day events, hosted by schools across the country, bring together parliamentary debaters from coast to coast. All debaters participate in the traditional five rounds of open competition, with top teams proceeding to elimination rounds. Individual speaking events may also be offered. Tournament resolutions will often be linked to a specific theme, and in addition to debate, tournaments offer free lodging for students in dormitory rooms, a tournament banquet, and an evening party or other entertainment. All APDA member schools are encouraged to host their own official, sanctioned tournaments if they wish.
In addition to the regular tournament schedule, APDA hosts an annual Novice Tournament, designed to introduce new participants to debate through competition and intensive training seminars; and the APDA National Debate Championship, which traditionally draws between 70 and 100 top teams from across the country. APDA members also participate in the North American Debate Championship (in conjunction with the Canadian University Society for Intercollegiate Debate), the World Debating Championship, and other tournaments in the United States and abroad.