This paper introduces the use of the VigilAgent agent methodology to develop monitoring systems. This work is based on the suitability of the specific characteristics of agency for developing monitoring systems. It is usual to develop them following an ad-hoc approach instead of using a methodology for achieving quality standards expected from commercial software. In this paper, the five phases of VigilAgent, namely System specification, Architectural Design, Detailed design, Implementation and Deployment, are introduced. The proposal is validated through the case study of controlling the access of human beings to a specific area.