This thesis aims to create a common understanding of how agile methodologies and lean thinking connect in project management and software development. This thesis will address how agile methods are used in start-ups and more prominent organizations and why agile has helped create a more fluent and valuable workflow. The perspective of this thesis is to observe the connection between agile and lean thinking and how they are used in management. Lean thinking is a mindset with the term coined by James P. Womack through his research of automobile production, later used in different environments such as software development. The goal of the mindset is to focus on the essential matters through the project while reducing the lack of "waste" and simplifying the workflow. This thesis was carried out as a literature review. Nine publications were selected for the literature review. The pieces of literature have been selected to each have a crucial element of agile or lean implemented in management and software development. The resources for the literature were all found through online database search tools and previous research on the matter. The first section of the thesis will present the topic and its use in this thesis. The second section is the literature review. The last section brings up conclusions and further discussion about agile and lean together. This thesis shows, there is a clear connection between agile and lean. The adaptive nature of both agile and lean makes it easier to be used simultaneously in any needed working environment. The numerous different methodologies make it difficult to understand the appeal and clear benefits for this thesis. However, the nature of adapting and using the methods is the advantage of agile and lean.