The primary object of inquiry is the semantics of the progressive and perfect constructions in English, and their interaction with the deictic category of tense. The domain of inquiry is text. The major concern is the argument that a full description of these constructions' development involves consideration of both functional (semantic- pragmatic) and formal (morphosyntactic) change. The bases of the framework constructed for analysis are Lyons' (1977; 1982) theory of locutionary subjectivism, and Traugott's (1982) model of semantic- pragmatic shifts in the grarrmaticalization process. Thus the description depends on the r ole of text in characterizing and shaping the meaning and use of auxiliary elements. Accordingly, I use a range of text-types for illustrative purposes. It is important to emphasize their exemplary function - they do not constitute a statistically defined or determined corpus. The main theme of this dissertation is the emergence of what I call the 'subjectivity' of these constructions in the context of their realization as grarrmatical markers of the English auxiliary. The study is divided into three parts. The first (chapters 1, 2, and 3) is a synchronic characterization of tense semantics focussing on subjectivity and text; and against this background, the semantics of the progressive and the perfect. The second part (chapters 4, 5, 6) is a detailed historical account of the perfect and the progressive in the framework of grarrmaticalization. A central concern of this section is the exploration of the semantic-pragmatic shifts forming part of the grarnnaticalization process. The last part, chapter 7, is an attempt to show the early instantiation of expressive meanings through the subjective function of tense, the progressive and perfect in experiential text- types, represented by the personal letter . The study is therefore organized cyclically, its major themes being the grarrunaticalization and semantic- pragmatic development of the English auxiliary, and their elucidation through text.