This research paper is devoted to the mathematical features of functional languages extended by control operators. More precisely, the goal is to show that a &lgr;- calculus, previously introduced by the authors [1], is a basis for developing a uniform framework for reasoning about control operators. Next, the authors add a more complex &lgr;-abstraction, of a dynamic nature, to capture delimiters of continuations, the so-called prompts. Finally, they reexamine the calculus in a logical perspective, exhibiting the part of the dual connective of implication. The paper ends with an extensive bibliography, with both recent entries, focusing on the state of the art, and more basic ones, to which the nonspecialist can refer. This is very useful; the paper presupposes a fine knowledge of the matter, and the presentation is very abstract.