George Andrews is one of the most influential figures in number theory and combinatorics. In the theory of partitions and q-hypergeometric series and in the study of Ramanujan's work, he is the unquestioned leader. To suitably honor him during his 70^th birthday year, an international conference on Combinatory Analysis was held at The Pennsylvania State University, December 5–7, 2008. Three issues of The Ramanujan Journal comprising Volume 23 were published in 2010 as the refereed proceedings of that conference. In view of the great interest that the mathematical community has in the influential work of Andrews, it was decided to republish Volume 23 of The Ramanujan Journal in book form, so that the refereed proceedings are more readily available for those who do not subscribe to the journal but wish to possess this volume.

The broad range of areas covered during the conference included the many facets of the theory of partitions, single and multi-variable q-hypergeometric series, various aspects of Ramanujan's mathematics, analytic number theory, and combinatorial number theory—areas which collectively were classified under the heading of Combinatory Analysis by MacMahon and his contemporaries in the early part of the twentieth century. As a fitting tribute to George Andrews, many speakers from the conference contributed research papers to this volume, which deals with a broad range of areas that signify the research interests of George Andrews. In reproducing Volume 23 of The Ramanujan Journal in this book form, we have included two relevant papers that appeared in other issues of the journal.