A study investigated the phonemic and morphophonemic patterning of the glottal stop in Agutaynen, a Meso-Philippine language, and some comparison with two northern Philippine languages. Agutaynen glottal stop has as its sole origin a neutralization of contrast rule, the operation of which can be noted in three different linguistic environments. Although it is not possible at this point to specify precisely all the factors influencing its application, the neutralization rule is apparently sensitive to social factors in this environment. It is hypothesized that the glottal stop in Agutaynen represents an innovation that has been spreading through the language for some time but which is currently being halted across a morpheme boundary by the influence of a more prestigious and increasingly used second language. The introduction of a glottal stop through neutralization of contrast is a little-documented phenomenon, but its presence in at least three languages (Agutaynen, Ga'dang, and Isnag) suggests that such a process may be even more widespread among Philippine languages that allow a preconsonantal glottal. Eighteen notes and an eight-item bibliography are included. (MSE)