The Collingridge dilemma-the problem of reacting to emerging technology either "too early" or "too late"-is one that is readily recognized by developers and promoters of nanotechnologies. One response can be found in the rise of a discourse of "responsible development" in the science and innovation policy landscape. While a number of commentators have discussed the potential of such initiatives, it remains unclear how responsible development is actually being configured "on the ground," in private sector nanotechnology. This paper addresses this question by analyzing empirical engagements in Europe and the United States in order to map industry operationalizations of "responsibility" in these contexts. We show that a number of different articulations of "responsibility" are present, including as a response to public lack of trust and perceived public pressure, and as the management of risk. We close by relating these findings to the theoretical literature on responsibility, other contemporary accounts of the ways in which responsible development can be operationalized, and the possibilities that these articulations of responsibility may open up.