This is the online appendix to the following **book chapter**: - Sönning, Lukas. (to appear). (Re-)viewing the acquisition of rhythm in the light of L2 phonological theories. In Robert Fuchs (ed.), Speech rhythm in L2 and L3 varieties of English. Singapore: Springer. The manuscript is available as a **preprint** on *PsyArXiv* (https://psyarxiv.com/x36jh/). Here is the **abstract**: - *Previous work on non-native speech rhythm has often drawn on L2 phonological theory for the interpretation of findings. The explicit confrontation of theory-derived hypotheses with data remains scarce, however. This paper illustrates how a hypothetico-deductive approach can contribute to our understanding of L2 speech rhythm. We consider cross-sectional data on prominence alternations in German learner speech from the viewpoint of two dynamic frameworks: The Ontogeny Phylogeny Model (OPM) and the Linguistic Theory of L2 Phonological Development (LTD). While both theories deal with L1-independent, universal forces in L2 acquisition, the OPM further considers the role of L1 transfer, similarity, and markedness. The predictions we formulate based on the two models lead us to pursue distinct methodological strategies. While our reading of the OPM prompts us to measure speech rhythm as a single, global category of speech, the LTD suggests a more nuanced, componential approach to L2 rhythm. Our application of the OPM confronts us squarely with the limited utility of rhythm metrics for L2 speech research and points to a number of issues at the theory-data interface. Overall, the LTD generates more informative predictions and provides a richer framework for the empirical study of prominence grading in L2 speech.* The study was first presented at BICLCE7 in Vigo, Spain, in 2017. The **presentation slides** can be found here: https://osf.io/9bzty **Data** used in the study have been published on TROLLing: - Sönning, Lukas. 2022. Speech rhythm in German Learner English: Dataset for “(Re-)viewing the acquisition of rhythm in the light of L2 phonological theories”, https://doi.org/10.18710/GTI2BR, DataverseNO, V1. **Images** created for this study can be found in the folder "figures". They are published under a Creative Commons Attribution 4.0 licence (**CC BY 4.0**), which means that the licence terms for their use are quite generous (see http://creativecommons.org/licenses/by/4.0). The files in the folder "R scripts" document the statistical analyses. They can be opened within R (or RStudio) or using a text editor. The output of the regression models (not included in the paper) can be accessed as an html file (folder: "Regression output") and opened in a web browser.