The aim of this research was to evaluate Farmer Field School's (FFS) capacity to boost the knowledge of farmers in Calabar Agricultural Zone, Cross River State, Nigeria. Specifically, the research aimed to describe the socio-economic characteristics of respondents; assess the effectiveness of FFS on training farmers, improving their knowledge and utilization of new technologies; and ascertain constraints faced by farmers in FFS training. The study adopted multi-stage and purposive sampling techniques to select 318 respondents. Descriptive statistics such as means and percentages were employed to analyze the data. The results revealed that most (64.5%) of the respondents were men; 39.3 and 86.5% were married with a mean household size of 6 persons. On participation, the results indicated that FFS was perceived to be effective in allowing farmers to participate highly in activities such as location of experimental site ( =2.94), experimenting with new methods and techniques ( =2.90) among others. From the findings, it was revealed that FFS was effective in training participants, such as in helping them to learn new ways of doing things in their farm ( =2.84) among others. Analysis of the results further revealed that Farmer Field School was effective in increasing the knowledge of participants on many factors in the farm environment. FFS was also perceived to be effective in influencing most of the participants to utilize about 71% of the technologies captured in this study. The most salient constraints uncovered by the study were non-availability of inputs, followed by inadequate trial and training materials. After thorough investigation and analysis, it was concluded that FFS is an effective agricultural knowledge booster. Based on the findings, it was recommended that FFS should be utilized to design and implement trainings, especially when introducing any innovation to farmers.