This paper analyses one specific conversational practice of formulation called ‘notionalization’. It consists in the transformation of a description by a prior speaker into a categorization by the next speaker. Sequences of this kind are a “natural laboratory” for studying the differences between descriptions and categorizations regarding their semantic, interactional, and rhetorical properties: Descriptive/narrative versions are often vague and tentative, multi unit turns, which are temporalized and episodic, offering a lot of contingent, situational, and indexical detail. Notionalizations turn them into (...) condensed, abstract, timeless, and often agentless categorizations expressed by a noun (phrase) within one turn constructional unit (TCU). Drawing on audio- and video-taped German data from various types of interaction, the paper focuses on one particular practice of notionalization, the formulation of purportedly common ground by TCUs prefaced with the connective also . The paper discusses their turn-constructional and morphological properties, pointing out affinities of notionalization with language for special purposes. Notionalizations are used for reducing detail and for topical closure. They provide grounds for emergent keywords, which can be reused to re-contextualize topical issues and interactional histories efficiently. Notionalizations are powerful means for accomplishing intersubjectivity while pursuing (sometimes one-sided) practical relevancies at the same time. Their inevitably perspective design thus may lead to re-open the issue they were deemed to settle. The paper closes with an outlook to other practices of notionalization, pointing to dimensions of interactionally relevant variation and commonalities. (shrink)