This paper utilizes a corpus based methodology to explore the diachronic development of the matrix verb feel in the construction [feel + that/zero + clausal complement].and the emergence of the collocation I feel in present day English as a grammaticalized ‘epistemic parenthetical’ (Thompson and Mulac, 1991). A total of 8357 tokens from 1351-2009 were analyzed. The effect of the following factors on the grammaticalization and (inter)subjectification of the matrix verb feel, and its current use as an epistemic parenthetical, were investigated: (i) the effect of the variation in use of the complementizer that vs. zero in (n= 1757) examples from 1351-2009; (ii) the diachronic statistical significance via a multivariate regression analysis of four structural factors which favour the zero-complementizer form and (iii) within the (n = 558) zero-complementizer constructions the presence and position (n=163) examples of feel being utilized as an ‘epistemic parenthetical’ (EP/EPAR). The analysis shows that the increased frequency of I feel zero-complementizer (vs. I feel that) correlates with increased subjectification. The analysis suggests that the I feel (MSP) subject-matrix collocation is undergoing grammaticalization via decategoralization, with the original matrix clause now functioning as a parenthetical disjunct much like I think/know/believe etc. (Nuyts, 2001; Thompson and Mulac, 1991).