This paper examines determinants of adoption of rainwater harvesting and conservation techniques in semi-arid Tharaka sub-county, Eastern Kenya. Given the erratic rainfall that characterises Tharaka, rainwater harvesting and conservation is critical for the improvement of agricultural production. The study was conducted in two agro-ecological zones, and 196 respondents were interviewed. The majority of the farmers were practising between 1-3 and 4-6 rainwater harvesting and conservation techniquesan indication of the awareness of the benefits. In situ technologies were more frequently practised than micro-catchment and macro-catchment technologies. There were institutional efforts supporting adoption of micro-catchment and macro-catchment techniques in the recent past. Correlation results showed that the number of techniques practised was influenced by the number of years spent in school, arable land size, labour availability and number of livelihood options. Soil quality is an unlikely determinant of rainwater harvesting because a majority of the farmers rated it as good and fair. Chi-squared results suggest that choice of rainwater techniques is primarily informed by a desire to harvest and conserve soil moisture than to improve soil quality. Although adoption of these technologies is encouraging, assessment of their efficiency in the context of physical attributes such as soil characteristics, slope and rainfall amount of the area would add value. Copyright (c) 2014 John Wiley & Sons, Ltd.