Cover crops may be an inappropriate intervention in many situations. This paper attempts to identify when and where cover crops are relevant to the requirements of different stakeholders. It is argued that donors, government institutions, environmental NGOs, and farming families often have different agendas and priorities, and that cover crops can fulfill different purposes for each set of actors. Cover crops occupy temporary niches during processes of intensification and integration of farming systems. The adoption/adaptation of cover crop technology within farming systems will depend on a range of factors, including technical appropriateness and economic viability, that define their systems "fit." Case studies from Central and South America are used to substantiate the points made.