The chair has two primary responsibilities for the ISA Conventions & conferences: 1) contacting participants prior to the meeting to set expectations and presentation time limits and 2) ensuring the flow of the panel onsite.
The chair's email communication should probably come no later than 3 weeks prior to the start of the an ISA Convention or conference. If chairing a panel, the chair should also remind panelists to share their papers (even in draft form) with their discussant no less than a week in advance and upload to paper archive. If chairing a roundtable, this entails circulating a detailed memo regarding the issues to be discussed by the participants.
The second aspect of the chair's responsibility is to organize the panel onsite. This includes briefly introducing the panel/roundtable to the audience and holding participants to agreed-upon time limits, as well as facilitating discussion and Q&A with the audience (approximately the final 30 minutes). Lastly, (for the ISA Annual Convention) chairs may be asked to complete a short survey of their panel/roundtable through the isanet.org system.
Chairs are also responsible for informing the Program Chair(s) of all changes to the panel or roundtable as soon as possible.