The differentiation of text segments to fulfil specific discourse functions (e.g. to introduce a topic, or to state the time and place of a story), along with the definition of clear textual boundaries that set the text apart from the situational context, are two aspects of the configuration of a text as an autonomous semantic unit. This paper analyzes the opening and closing elements of narrative and expository texts to determine whether they function as well defined boundaries, and fulfil a specific discourse function with respect to the text as a whole. The population for this study consisted of 120 participants, 10 at each of the Age levels of grade school, junior high, high school, and university, yielding 40 participants in each of three target Languages: English, Spanish, and Swedish. The database included 480 texts divided by Modality (written vs. spoken) and Genre (narrative vs. expository). All text openings and closing were coded for positioning, i.e. the framework used by speaker/writers to introduce or conclude the topic developed in their texts, and for functioning, i.e. the role these elements play in the text. Results showed that, as texts become more “detached” from the situation in which they are produced, their component parts become more functionally differentiated. This process is described first in the openings of narrative and expository texts, and later in the closings of expository texts; narrative closings remain a problematic area of text construction for most speaker/writers in this study, in every Age group. These processes of detachment and internal functional specification of text components occurred earlier in writing than in speech. The cross-linguistic differences found in the study are related to different teaching practices, rather than to language specific features