Situated within the framework of the systemic-functional linguistics (Halliday, 1994) and language-based theory of learning (Halliday, 1993), this article examines a shift toward a more objectified and "scientific" representation of reality in texts written by foreign language (FL) learners at various levels of acquisition. It argues that linguistic variation in style impacting communicative effectiveness of written texts created by learners representing different levels of FL acquisition can be partly captured by means of grammatical metaphor, as a phenomenon of "transcategorization," whereby processes (typically realized by verbs), attributes (typically realized by adjectives), or whole propositions (typically realized by sentences) are encoded as nouns. Based on a study conducted on 55 book reviews written by advanced American learners of German and 30 texts written by native speakers in the same genre, the article identifies various types of grammatical metaphors or approximations toward it as characteristic of various acquisition levels. It also demonstrates the role and functions of grammatical metaphor in enhancing the ability of writers to construct a logical argument or a persuasive evaluation. Comparisons to the use of grammatical metaphor in the texts produced by native writers of German show it to be a prominent feature of adult language use in literate and academic contexts, by native or nonnative language users.