Dynamic binding is a runtime operation which looks up some names in some environments: examples are quote and eval in LISP or object-oriented message passing. We present a functional language, in the spirit of ML or Haskell, which supports dynamic binding. At the surface level, the language supports constructs such as extensible records, variants, extensible case selection, quoted terms, and can encode various forms of objects. The underlying execution model is a lambda-calculus with name-based (labels, keywords) parameter passing. The type system supports subtyping, through an extension of Hindley-Milner type inference with recursively constrained types.