There are a fair number of suffixes in English whose conditions on attachment refer to stress and/or segmental information contained within the words they attach to (see Siegel 1974, Jespersen 1942 and Marchand 1969). Through a wide study of relevant data, we will delve deeply into such phonological restrictions on the bases, which may as well be divided into four distinct types: haplological constraints; segmental constraints; prosodic constraints; and mixed types. We will further assume here that the category/ subcategorization requirements of affixes are subject to the Projection Principle (PP) as conceived in Kiparsky (1983). It will be shown how this PP interacts with phonological constraints placed upon the affix in question, especially in the treatment of-ful (inventful/mournful) or -en (longen/lengthen). Our account of problematic affixations in English is based on a number of violable constraints in OT.