Driven by the pressure to permanently release a large number of books, publishers have to allocate limited advertising budgets across the wide range of newly released books. As in many creative industries, publishers often focus their advertising activities on potential top sellers written by recent bestselling authors. Considering potential selection effects in choosing the “right” books for advertising, this paper investigates (1) whether selection effects exist and to what extent potential selection effects influence the relation between book advertising and book sales and (2) the boundary conditions under which book advertising leads to higher sales by focusing on the “star power” effects of authors. By applying propensity score matching to a dataset of 598 fiction books from the German book market, we identify substantial selection effects that lead to a serious overestimation of advertising effectiveness by up to 41 % (10,000 copies sold). Using group analyses, we find that sales of books written by recent bestselling authors are not significantly influenced by advertising activities of publishers; however, the sales of books written by lesser-known authors can be increased significantly if they are advertised. Our findings are highly relevant for publishers, indicating that a shift in the allocation of advertising budgets toward promising books by lesser-known authors is recommended to improve the overall advertising effectiveness.