This book contains the papers accepted for presentation and publication in the wo- shop proceedings of the 28th edition of the International Conference on Conceptual Modeling (ER Conference), held during November 9-12, 2009, in Gramado, Brazil. The ER workshops complement the main ER conference and are intended to serve as an intensive collaborative forum for exchanging late-breaking ideas and theories in an evolutionary stage and related to conceptual modeling. For the 2009 edition the workshop committee received 14 excellent proposals from which the following were selected: - ACM-L: Active...