Major advances in donor identification and probes and methods to clone pathogen-specific antibodies have been realized over the past years, leading to exponential growth in the number of newly characterized broadly neutralizing antibodies (bnAbs) to the HIV-1 envelope, as well as to the identification of new epitopes and novel modes of antigen recognition. However, the ability to translate envelope recognition into an understanding of in vivo activity has lagged behind, and identification of blood samples or monoclonal antibodies with potent anti-viral activity has generally remained reliant on empirical evaluation of neutralization potency and breadth. Here, we undertook a study to evaluate the fine epitope specificity of a panel of CD4 binding site (CD4bs) antibodies, and in doing so, we defined the molecular recognition features of functionally potent antibodies targeting the HIV envelope CD4bs. Whereas previous studies have used neutralization data and machine learning methods to provide epitope maps, here, we reversed the process, and demonstrated that fine epitope specificity can prospectively identify broadly neutralizing CD4bs-specific monoclonal antibodies. Building on this result, we further showed that epitope mapping and effective predictions of neutralization breadth can also be achieved in the assessment of polyclonal serum responses. Bringing the discovery loop full circle, we are investigating the use of a novel probe of CD4bs neutralization breadth signature residues in identification of novel CD4bs bnAbs.