Mounting ring for installing a built-in light in an installation opening formed in a ceiling or wall element, comprising - a ring-shaped base element with a flange region for abutting against the ceiling or wall element and - at least one holding element for holding the base element in the installation opening, wherein the at least one holding element is arranged in a movable manner opposite the base element such that it can be moved back and forth between a mounting position and a holding position, wherein the mounting ring can be moved into the installation opening when the at least one holding element is in the mounting position and wherein the mounting ring is held in the installation opening when the base element is positioned as intended in the installation opening and the at least one holding element is in the holding position, wherein the mounting ring is designed in such a way that the at least one holding element is movably arranged on the base element in such a way that it cannot be separated from the base element without changing the form of the base element or of the at least one holding element, wherein the at least one holding element has first guide elements (6, 7, 8, 9) for the movable arrangement on the base element and the base element has second guide elements (10, 13, 10', 11', 12', 13') which interact with the first guide elements (6, 7, 8, 9) such that the at least one holding element is arranged in a guided and movable manner on the base element, characterized in that the first guide elements (6, 7, 8, 9) comprise a guide pin and the second guide elements (10, 13, 10', 11', 12', 13') comprise a guide surface for guiding the guide pin, or the first guide elements (6, 7, 8, 9) comprise a guide surface and the second guide elements (10, 13, 10', 11', 12', 13') comprise a guide pin. - a ring-shaped base element with a flange region for abutting against the ceiling or wall element and - at least one holding element for holding the base element in the installation opening, wherein the at least one holding element is arranged in a movable manner opposite the base element such that it can be moved back and forth between a mounting position and a holding position, wherein the mounting ring can be moved into the installation opening when the at least one holding element is in the mounting position and wherein the mounting ring is held in the installation opening when the base element is positioned as intended in the installation opening and the at least one holding element is in the holding position, wherein the mounting ring is designed in such a way that the at least one holding element is movably arranged on the base element in such a way that it cannot be separated from the base element without changing the form of the base element or of the at least one holding element, wherein the at least one holding element has first guide elements (6, 7, 8, 9) for the movable arrangement on the base element and the base element has second guide elements (10, 13, 10', 11', 12', 13') which interact with the first guide elements (6, 7, 8, 9) such that the at least one holding element is arranged in a guided and movable manner on the base element, characterized in that the first guide elements (6, 7, 8, 9) comprise a guide pin and the second guide elements (10, 13, 10', 11', 12', 13') comprise a guide surface for guiding the guide pin, or the first guide elements (6, 7, 8, 9) comprise a guide surface and the second guide elements (10, 13, 10', 11', 12', 13') comprise a guide pin.