<p>Argument alternations are an empirical mainstay in studying the building blocks of verb meaning and how such meanings link to a verb’s grammatical properties. Event structures are widely adopted for exploring these questions, where a verb’s meaning is decomposed into an event template (defining grammatically coherent verb classes) and a root (filling in idiosyncratic verb-by-verb details). An alternation is analyzed as one root occurring in two templates, the latter supposedly predicting most of the properties of the alternation. Yet, idiosyncratic roots also have a significant effect in determining which alternations they occur in and the two variants’ interpretations. Beavers and Koontz-Garboden (2020) proposed that roots can also introduce the same templatic information as templates, in ways that explain such root-specific effects through compositional interactions of root and template meanings. We explore the explanatory power and limits of this ‘root semantic’ approach by expanding its empirical scope to an alternation similar to a dative alternation in Kinyarwanda (Bantu JD61; Rwanda), which are derived via the applicative morpheme <i>-ir</i>. The broad productivity of <i>-ir</i> in forming ditransitives, coupled with the significantly wider range of root-specific interpretative and grammatical effects, provides an ideal case study for the role of idiosyncratic verbal meaning in governing argument alternations. We show that a root semantic approach naturally captures the diversity of root-specific effects in Kinyarwanda, justifying it as part of a general theory of alternations. However, ingredients from work that has syntactified constraints on alternations or posited allosemic variation in templatic meaning are also needed, resulting in a multifactorate understanding of alternations with root semantics at its core.</p>