Introduction, Main Conclusions and Recommendations of the Workshop `QSAR Biodegradation II'; W. Peijnenburg, J. Damborský. Part I: Biodegradability (foundations, testing). Biodegradability of Xenobiotic Organic Compounds Depends on their Chemical Structure and Efficiently Controlled, and Productive Biochemical Reaction Mechanisms; R.-M. Wittich. Biodegradability Testing of Xenobiotics; P. Pitter, V. Sýkora. Part II: Biodegradability Modelling (trends, methods). The META-CASETOX System for the Prediction of the Toxic Hazard of Chemicals Deposited in the Environment; G. Klopman. Application of Artificial Intelligence in Biodegradation Modelling; D. Gamberger, et al. Polychlorinated Dibenzo-p-Dioxins in Anaerobic Soils and Sediments. A Quest for Dechlorination Pattern-Microbial Community Relationships; P. Adriaens, et al. A Biodegradability Evaluation and Simulation System (BESS) Based on Knowledge of Biodegradation Pathways; B. Punch, et al. A Mechanistic Approach to Deriving Quantitative Structure Biodegradability Relationships. A Case Study: Dehalogenation of Haloaliphatic Compounds; J. Damborský, et al. Part III: Biodegradability Prediction (Applications). Quantitative Structure-Biodegradability Studies: An Investigation of the MITI Aromatic Compound Data-Base; J. Dearden, M. Cronin. Prediction of Biodegradability from Chemical Structure: Use of MITI Data, Structural Fragments and Multivariate Analysis for the Estimation of Ready and Not Ready Biodegradability; H. Loonen, et al. Development of Structure-Biodegradability Relationships (SBRs) for Estimating Half-Lifes of Organic Contaminants in Soil Systems; R. Govind, et al. Index.