In the field of outcomes research, modeling is increasingly being used to assess costs and outcomes associated with healthcare interventions. However, there is little standardization with regard to modeling practices, and the quality and usefulness of economic and health outcomes models may vary. We propose the following set of recommendations for good modeling practices to be used in both the development and review of models. These recommendations are divided into three sections: criteria to be addressed before model development or initial review; criteria used during model development or evaluation; and criteria used following model development. These recommendations also include examples regarding different modeling techniques and practices as well as a checklist (see appendix) to assess model correspondence with the recommendations. We hope that the use of good practice recommendations for modeling will not only improve the development and review of models but also lead to greater acceptance of this methodology.