This PhD project is entirely focused on the under-researched (according to e.g. Hundt & Leech 2012, Hundt 2014) topic of grammatical obsolescence understood as a situation in which a previously popular and productive construction is losing its productivity and popularity over time. There are several “subgoals” of the project, namely i) to develop a theoretical approach to loss and decline of grammatical constructions; ii) to offer practical insights into the process of grammatical obsolescence – with an empirically-based case study; iii) to analyze and describe possible causes and explanations for the observed cases of grammatical obsolescence comparing them with findings from the literature (e.g. Ashby 1981, Hund & Leech 2012, Hilpert 2012, Hundt 2014), and, at the same time, situating grammatical obsolescence in the landscape of language change processes. Methods: Grammatical obsolescence is often a very gradual and long process that proceeds until the construction disappears or there are only residues/ fossilized forms left. The function of the obsolescent construction may discontinue or continue to be (fully or partially) expressed by alternative means. An important part of the project was to formalize this observation by means of the “criteria catalogue” designed for the investigation of potentially obsolescent constructions. The methodology is based on a combination of statistical analysis of data extracted from different language corpora. The investigated variable: Subordination of purpose. The PhD project focuses on the following variants: in order to ( in order not to) – infinitival clause without notional subject; in order that – finite clause; in order for * to – infinitival clause with notional subject (for-NP); so as to (so as not to) – infinitival clause without notional subject; lest (negative purpose) – finite clause. References Ashby, W. 1981. The loss of the negative particle ne in French: a syntactic change in progress. Language 57: 647 – 660. Hilpert, Martin. 2013. Constructional change in English: developments in allomorphy, word formation, and syntax. Cambridge: CUP. Hundt, M. & Leech, G. 2012. Small is beautiful: On the value of standard reference corpora for observing recent grammatical change. In Nevalainen T. & Traugott E. (eds.), The Oxford handbook of the history of English. New York: Oxford University Press. 175–88. Hundt, M. 2014. The demise of the being to V construction. Transactions of the Philological Society 112(2): 167-187.