This study proposes to examine the phonetic ongm of the Latin diminutive suffixes in -ellus -a -um and -illus -a -ttm , and to trace the lines of their analogical extension as independent formative elements, a phenomenon which is later than the origin of -ello/ā and -illo/ā- through phonetic processes. Since scholars have expressed several opinions on the phonetic origin of these suffixes, it is perhaps justifiable to examine the validity of the view most commonly held, by adducing all the extant pertinent materials, inasmuch as no such detailed presentation has yet, to my knowledge, been made. Moreover, little or no consideration has been given to the problem of the extension of the suffixes -ello/ā- and -illo/ā- from words or groups of words where their development was phonetic, and of the possible points of departure of this extension.