The objective of the thesis is to evaluate to what extent rainfall or presence of irrigation systems, influences Kenyan and Tanzanian Farmers implementation of crop diversification. The period of time considered is from 1990 to 2020. To address this goal, the thesis will examine how seasonal variability and spatial distribution of rainfall can encourage or discourage farmers from diversifying crops, as inconsistent rainfall may force them to diversify to reduce crop failure risk. Additionally, it will assess how the availability and efficiency of irrigation systems affect diversification decisions, as irrigation can mitigate risks associated with scarce rainfall and provide greater flexibility in crop choice. The thesis will rely on data collected from interviews with local farmers, climate analysis, and reviews of existing literature to determine which factor has a greater impact on crop diversification decisions in Kenya and Tanzania.