This monograph develops an algebraic approach that can be used to construct convolutional codes that are efficient in both classical and nonclassical situations. Coding theory, which is an offshoot of the field of probabilistic information theory, falls into two parts: block codes and convolutional codes. Block codes have lent themselves to easy and efficient construction by the use of certain algebraic tools, but rarely have those tools been of any use in constructing convolutional codes. These are generally constructed by methods of computer search. Convolutional Codes makes a significant contribution to the field of coding theory by presenting an original construction scheme for convolutional codes that makes them more powerful and easier to analyze than codes generated by the more usual method of computer search. The algebraic approach, Piret points out, is used not because of itself, but for its efficiency in constructing and analyzing convolutional codes having good and various error correcting capabilities. Philippe Piret is a member of the Philips Research Laboratory in Brussels