There is a need to develop viable farming systems for tropical uplands dominated by low-activity clay soils; such systems should ensure sustained crop production while protecting the soil resource base. Alley cropping has the potential to meet this need. For over a decade, the alley cropping technique has been tested, with varying results, in various agroecological zones. Results obtained thus far show that the best potential is on the high base-status soil in the humid and subhumid zones, and that crop production can be sustained in this ecozone with low chemical inputs. Further research is needed for other ecozones, particularly with inclusion of better adapted or indigenous hedgerow species. The potential and limitations of the alley cropping technique are highlighted and areas of future research discussed.