The objective of this project is to develop an animal-based indicator system for the assessment of laying hen welfare on-farm and at the slaughterhouse for farm auditing purposes. Based on an extensive literature review, appropriate animal-based indicators are selected and detailed descriptions and illustrations of the assessment methods provided. The proposed scoring schemes are tested in a field study on commercial farms and slaughterhouses with regard to their reliability and feasibility. Based on the findings of the practical tests on the project farms and at the slaughterhouse, indicator selection and method descriptions are critically reviewed and modified, if necessary. Subsequently, training material such as practical guidelines and assessment cards for auditors and slaughterhouse employees are compiled.