Agile software development methodologies gaining the attention in the field of software engineering. There are several methods of agile such as Scrum, Lean, and Kanban. Scrum methodology divides the product into series of sprints. Lean is agile toolkit which has seven principles that facilitate: eliminating the wastes, delivering fast, and improving value for the final customer. Kanban is a visual method that can help in managing the production. To take the advantages of the following methodologies: Lean, Scrum, and Kanban we can integrate them together thus, the result will be a new methodology that can contribute in enhancing and improving the efficiency of the software development process, which is the aim of this thesis. An integrated methodology that integrating Scrum, Kanban, and Lean methodologies to yield a comprehensive agile methodology called L-ScrumBan has been proposed. The validation of the proposed methodology has been done through a survey by using a questionnaire; the survey results confirmed the efficiency of the proposed methodology.