In Questioning Technology, Feenberg accuses Heidegger of an untenable 'technological essentialism'. Feenberg's criticisms are addressed not to technological essentialism as such, but rather to three particular kinds of technological essentialism: ahistoricism, substantivism, and one-dimensionalism. After these three forms of technological essentialism are explicated and Feenberg's reasons for finding them objectionable explained, the question whether Heidegger in fact subscribes to any of them is investigated. The conclusions are, first, that Heidegger's technological essentialism is not at all ahistoricist, but the opposite, an historical conception of the essence of technology which serves as the model for Feenberg's own view. Second, that while Heidegger does indeed advocate a substantivist technological essentialism, he offers a plausible, indirect response to Feenberg's voluntaristic, Marcusean objection. Third, that Heidegger's one-dimensional technological essentialism is of a non-objectionable variety, since it does not force Heidegger to reject technological devices in toto. These conclusions help vindicate Heidegger's ground-breaking ontological approach to the philosophy of technology.