The theory of overconvergent modular symbols, developed by Rob Pollack and Glenn Stevens, gives a beautiful and effective construction of the p-adic L-function of a modular form. They define a ‘specialisation map’ from the space of overconvergent modular symbols to the space of classical symbols, and the crux of their theory is a ‘control theorem’ that says that this map is an isomorphism on the small slope subspace. This gives an analogue of Coleman’s small slope theorem in the modular symbol setting. In this talk, I will describe their results, and then discuss an analogue of the theory for the case of modular forms over imaginary quadratic fields, for which similar results exist.