This article presents a convenient and efficient procedural interface that allows the definition and use of procedures with optional arguments and indefinite numbers of arguments without resorting to the use of a language-dependent data structure in which to store the arguments. This interface solves many of the problems inherent in the use of lists in Lisp and Scheme to store indefinite numbers of arguments. Simple recursion can be used to consume such arguments without the complexity problems that are caused by the use of the Lisp procedureapply on argument lists. A natural extension to the interface to support multiple return values is presented.