IAU Transactions XXIXA reports on the IAU Commissions that were created at the very first IAU General Assembly in Rome in 1922, and were terminated by the Executive Committee during the XXIX General Assembly in Honolulu in 2015. It includes the final Business Meetings of these 'old' Commissions and Working Groups (which historically appeared in the Transactions of the IAU 'B' volumes). In addition to these transactions, many of the Commission Presidents have enhanced their contributions with historical perspectives on their Commissions, going back in time a couple of triennia, sometimes longer. This volume, subtitled Commission Legacy Reports, is therefore unique in the organisation's history. It signals the end of an era, and the beginning of another, looking ahead to the organisation's 100th anniversary in 2019, whose celebrations will begin at the XXX General Assembly in Vienna in 2018.