The article explores ways in which clergy and laity build the Communio Ecclesiae, which is in line with the current theme of synodality. The publication presents both the theological foundations of building an ecclesial community and practical guidelines or building princiles. First comes the explanation of the understanding of Communio Ecclesiae. Next, the issue of “building” is dealt with, with attention being paid to its correlation with the idea of the Church, which is God’s building. The third point distinguishes and discusses four areas of cooperation: liturgical and sacramental, administrative and economic, along with charitable and formative. Finally, the principles of building Communio Ecclesiae are indicated and these focus on the conditions of the Church in Poland, which are essentially of a practical nature. Building an ecclesial community should be accompanied by an awareness of participation in the saving mission of Christ and a conviction of the multiplicity and diversity of services and tasks in the Church. Building up of the Communio Ecclesiae is not an end in itself; rather, it is a path leading to the salvation of the faithful and the fulfilment of the Church in the kingdom of God in eschatological times.