He worked primarily in number theory, with specific interests in p-adic analysis and arithmetic geometry. In particular, he developed a theory of p-adic integration analogous to the classical complex theory of abelian integrals. Applications of Coleman integration include an effective version of Chabauty's theorem concerning rational points on curves and a new proof of the Manin-Mumford conjecture, originally proved by Michel Raynaud. Coleman is also known for introducing p-adic Banach spaces into the study of modular forms and discovering important classicality criteria for overconvergent p-adic modular forms. With Barry Mazur, he introduced the eigencurve and established some of its fundamental properties. In 1990, Coleman found a gap in Manin's proof of the Mordell conjecture over function fields and managed to fill it in. With José Felipe Voloch, Coleman established an important unchecked compatibility in Benedict Gross's theory of companion forms.[citation needed]
Coleman's effective version of Chabauty's method only applies to curves that satisfy Chabauty's condition. In 2004 Minhyong Kim published a far-reaching generalization of Chabauty's method.[4][5]
Coleman, Robert F. (1985), "Torsion points on curves and p-adic abelian integrals", Ann. of Math., 121 (1): 111–168, doi:10.2307/1971194, JSTOR1971194, MR0782557