This book provides a computational re-evaluation of the genealogical relations between the early Germanic families and of their diversification from their most recent common ancestor, Proto-Germanic. It also proposes a novel computational approach to the problem of linguistic diversification more broadly, using agent-based simulation of speech communities over time. This new method is presented alongside more traditional phylogenetic inference, and the respective results are compared and evaluated. Frederik Hartmann demonstrates that the traditional and novel methods each capture different aspects of this highly complex real-world process; crucially, the new computational approach proposed here offers a new way of investigating the wave-like properties of language relatedness that were previously less accessible. As well as validating the findings of earlier research, the results of this study also generate new insights and shed light on much-debated issues in the field. The conclusion is that the break-up of Germanic should be understood as a gradual disintegration process in which tree-like branching effects are rare.