Impact of Cluster Front Line Demonstration on Yield and Economics of Mustard Dr. Ashok Kumar1 and Dr. Maya Kumari2 1 SMS (Extension Education), KVK, Gaya (Bihar) - 823003 2Scientist (H.Sc.), KVK, Sahibganj (Jharkhand) - 816109 The present study was done by krishi Vigyan Kendra, Manpur, Gaya in order to know the impact of CFLD via Yield Gap, Economic Return, Extent of farmer’s satisfaction and Constraints faced by the mustard growers. In the present investigation, 100 respondents selected randomly were all those farmers where CFLD on Mustard (Var. RH 0749) was conducted on their fields during the years 2020-21 and 2021-22.The inputs like improved seed, Biofertilizers, Suphur, fungicide, ect were provided by the KVK, Manpur. Before conducting CFLD, the respondents were made acquainted with the latest recommended package of practices of Mustard. The demonstrated technologies under CFLD resulted in an increase in yield by 45.7 percent over Local Check. It was also observed that there was technology gap (TG), extension gap (EG) and technology index (TI) of 10.25q/ha, 7.42 q/ha and 39.42 percent respectively. It was also revealed that there was additional return of Rs.32098/ ha with additional cost of cultivation of Rs.4081/ha & BC ratio of 2.91 for demonstration and 1.90 for Local Check. The respondent satisfaction index (RSI) revealed that maximum of the respondents expressed high level of satisfaction (61.00 percent) about CFLD followed by medium (36.00 percent) and least had low (3.00 percent). Out of many constraints identified, the main hurdle in increasing acreage under mustard cultivation was lack of availability of irrigation water ranking I.