This paper analysis promises made by companies to various publics, including global investors, national public administrative bodies and local populations. We speak of ‘promise engineering’ to describe both the integration of the making of promises in mining exploration operations and the attempted articulation of promises made to different publics with different concerns. We focus on the French ‘mining revival’, which prompted exploration projects that became controversial and were integrated into a government-led approach meant to introduce an objective of ‘responsibility in mining operations. Mining junior companies attempted to make promises that were both technical and social, while responsibility proved consistent with the crucial role of financial investment. We show that promise engineering offers an analytical lens for studying anticipation practices in industrial projects and the opposition these projects face.