The article analyzes the historical evolution of social democracy and its impact on labor law and social security from the 19th century to the second half of the 20th century. The main objective is to describe how social democracy developed as a response to liberal capitalism and communism, proposing a path of democratic reforms that protected workers’ rights and promoted equality. To achieve this objective, the article employs a historical and analytical approach that allows understanding the social and political context that gave rise to social democracy, comparing it with other ideologies such as Marxism and classical liberalism. Additionally, a comparative and critical analysis is used to examine the relationship between social democracy and the development of labor law and social security. The main findings show that, unlike communism, social democracy adopted a democratic and gradual approach to achieving social reforms, respecting liberal democracy and civil rights. Social democracy played a crucial role in building the welfare state, especially after World War II, ensuring labor rights and social protection systems that contributed to improving the working class’s living conditions. In conclusion, social democracy proved to be a viable alternative to uncontrolled capitalism, promoting the idea that state intervention is essential to guarantee freedom and social justice. © 2024, University Institution of Envigado. All rights reserved.