An important issue with regard to the overall effectiveness of conservation-tillage practices in reducing the impact of agricultural production on the environment concerns what happens to energy, pesticide and fertilizer use as these practices are more extensively adopted. To gain some insight into this, the conservation-tillage adoption decision is modeled. Starting with the assumption that the conservation-tillage adoption decision is a two-step procedure - the first is the decision whether or not to adopt a conservation-tillage production system and the second is the decision on the extent to which conservation tillage should be used - appropriate models of the Cragg and Heckman (dominance) type are estimated. Based on farm-level data on corn production in the USA for 1987, the profile of a farm on which conservation tillage was adopted is that the cropland had above-average slope and experienced above-average rainfall : the farm was a cash grain enterprise, and it had an above-average expenditure on pesticides, a below-average expenditure on energy and a below-average expenditure on custom pesticide applications. Additionally, for a farm adopting a no-tillage production practice, an above-average expenditure was mane on fertilizer.