The present report of Commission 15 has been, as usual, prepared primarily by the chairpersons of the two working groups. E. Tedesco wrote the section about Asteroids and Meteorites, with the assistance of A. Cellino, G. Consolmagno and C.-I. Lagerkvist. W. F. Huebner prepared the section about Comets, with the assistance of J. Benkhoff, H. Boehnhardt, J. Brandt, M. T. Capria, A. Cochran, G. Cremonese, M. Duncan, W. Huntress, H. Levison, and G. P. Tozzi. Moreover, the whole document has been assembled by K. Muinonen, who did the final editing, to merge the two reports and fit the document into the allotted space. Material taken from both major areas regarding the relationship between comets and asteroids has been combined into a single section.