This five-year study of the peer-led team learning (PLTL) paradigm examined its implementation in a Calculus I course at an all-male HBCU institution. For this study we set up a strong control group and measured the effect of PLTL in the teaching and learning of Calculus I through two points of measure: retention and success rates and learning gains. Our analysis reveals those aspects that can make the implementation of PLTL in calculus and perhaps in mathematics in general challenging and also shows hopeful aspects that promote better learning of the subject.