This book presents the first detailed empirical study of irregular verb morphology in the German-English interlanguage. Starting with a theoretical in-depth account of irregular verb morphology both in English and German, three widely discussed theses about its nature are tested against a wide range of empirical data, both from L1 and L2. Although the findings partly confirm existing models and theories, the data also show the need for further re-examination of some fundamental questions through associative or probabilistic computer models. All in all this book provides a rigorous, profound and thought-provoking discussion of the phenomenon in question, involving an up-to-date revision of existing theories as well as the cross-linguistic examination of L1 and L2 data by an array of sophisticated multivariate statistical models. It is mainly directed towards university students of German and English linguistics, psycholinguistics and language acquisition at an advanced level.