For centuries Jeddah has been the principal entrepôt to western Arabia and the gateway to the Holy Cities of Mecca and Medina. This work covers the period 1970-1984 during which, under the writer's personal direction on site in Jeddah, the city’s first comprehensive development plan was formulated and implemented. In narrative style, this thesis describes the preparation and monitoring of the original plan and its subsequent review by others. With the benefit of hindsight and personal experience, the writer offers an explanation for the successful realisation of the development plan despite an unforeseen four-fold growth in population over this fifteen year period. It can be concluded that this was due principally to the active and harmonious participation of a locally appointed composite Saudi technical team with the Consultant's British planning team and the inspired leadership of Engineer Mohammed Said Farsi, Mayor of Jeddah. The flexible philosophy and format of the plan enabled it to be modified in consequence of unforeseen changes to the Kingdom’s base economy arising from the increased demand for petroleum products in 1973. This approach to city planning is identified as making a major contribution to the successful realisation of the original objectives of the plan.