The application of knowledge to new contexts (i.e., transfer) is a central aim of learning processes and has become a new focus of testing effect research. In a quasi-experimental design, we investigated the transfer of retrieval practice effects on English vocabulary learning on eighth-grade students (N = 182) by applying a typical testing effect study paradigm including study, initial test or restudy, and final test. The final test comprised four test formats, one identical to the initial test (non-transfer context), and three deviating from the initial test (transfer context). Comparing testing and restudy conditions yielded a significant multivariate effect of testing across all final test formats and significant univariate effects in three of the four test formats. Comparing transfer and non-transfer contexts revealed smaller retrieval practice effects when transfer was required. The results are discussed against the theoretical background of transfer-appropriate-processing, elaborative retrieval, and a distribution-based model of retrieval.