In the first centuries of the Church, the Roman Pontiffs expressed the need for assistants because no one can perfectly perform all the tasks alone, especially if there are more of them or if they are more important. So, the need arose for the formation and organization of the Roman Curia, and its arrangement is the result of a long-term process. As the title suggests, this paper is devoted to the historical-legal analysis of the Roman Curia. The paper is divided into three chapters. The first chapter presents the concept of the Roman Curia. The emphasis is on historical review and Curia’s essence, but also its legal frameworks that it has gained through history. The more the Church grew and expanded, the more it strengthened its structure and organization. Therefore, the Roman Curia was subject to change. Thus, the second chapter describes the reform of the Roman Curia during the time under Paul VI., and John Paul II. The Apostolic Constitution on the Roman Curia, Pastor Bonus, and the organization of the Roman Curia are discussed in detail. The changes are shown in the Roman Curia that are brought by Pope Benedict XVI. In the third chapter is shown Pope Francis’s work and commitment to reform the Roman Curia and his fundamental thoughts on the Curia. A document is presented that completed the long-awaited reform of the Roman Curia - the Apostolic Constitution Praedicate Evangelium. The structure of the Roman Curia is shown and the innovations introduced by the reform are highlighted. The paper concludes whith a conclusion on the importance of the Roman Curia and its activities, but also on the constant changes that aimed to adapt it to the requirements of the time, and to make the institutions of the Roman Curia more suitable for achieving the purpose for which they are established.