Increase in agricultural productivity is induced by public investment in research. Several studies have analyzed the impact of research investment at the national level but such analyses at the state or regional level are a few. The present study is an attempt to analyze the pattern and quantify the returns to research investment made over a period of 25 years on major field crops such as rice, jowar, finger millet (ragi), red gram, groundnut, sunflower, cotton and sugarcane in a predominantly agrarian state of Karnataka in peninsular India. The impact of research investment was assessed in terms of technology developed and growth in total factor productivity. The agricultural research investment had profound effect on the development of technologies relating to crop varieties, plant protection and crop management: dominant in cereals and associated with higher research investments, which is in tune with the national objective of achieving food security. Consequently, the rate of return to research investment is quite high in case of rice and sugarcane, moderate for finger millet, cotton and jowar, negative in red gram, groundnut and sunflower. The TFP growth is also higher in crops that attracted higher research investments due to growth in yield as a result of continuous upgradation of technologies. There is a need to achieve higher level of productivity through enhanced research investment for most crops in the state particularly for pulses and oilseeds in order to achieve nutritional security as the state is already food secured.