The Baton Rouge Refinery of Humble Oil & Refining Company is implementing an advanced computer control system on their new in-line motor gasoline blending facilities. This paper first deals with the complexities of gasoline blending which dictate the use of both off-line and on-line computers. It then discusses the major functions of the computer system which include: the planning, scheduling, optimization, and control of all motor gasoline blending operations within the refinery. The system involves three digital computers, an extensive communications network, and some advanced on-line analyzers. This project is illustrative of a multilevel, multicomputer control system which has been designed to solve a number of complex problems for a number of different users within the refinery.