In 2006 the Kenya Tea Development Agency (KTDA) and Lipton jointly started a pilot project with funding from the UK government in Kenya. This pilot project introduced Farmer Field Schools (FFS) as an extension method, which aimed to improve the sustainability of tea production by increasing the rate of adoption of Good Agriculture Practices (GAPs) and to improve the profitability of small-holder tea producers. Because this pilot was a success, the FFS approach was up-scaled, KTDA, Uniliver and Rainforest Alliance (RA), assisted by the Sustainable Trade Initiative (IDH), started with training farmers in 2010 so that the tea factories and the smallholders would become Rainforest Alliance certified under group certification schemes. Because all parties involved expressed an interets to track whether the FFS approach and the training for RA certification indeed makes a difference in sustainability outcomes for smallholder tea producers, LEI Wageningen UR has been asked to conduct an impact assessment of both activities.