A joining and levelling system suitable for being used in furniture and furnishing items with a bottom and at least one shoulder positionable with respect to a floor the joining and levelling system comprising, in combination, at least one front foot unit (14,114) and at least one rear foot unit (15,115), wherein each front and rear foot unit (14,15; 114,115) comprises at least one connection group and a blocking group of a joining device for stably interconnecting said bottom and said at least one shoulder, wherein said connection group and said blocking group of the joining device can be actuated, when mounted, from the front of the furniture, said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) are suitable for being positioned beneath said bottom and facing said at least one shoulder, wherein said bottom and said at least one shoulder do not rest on the floor, said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) are positioned in an identical body (16,116) for both said at least one front foot unit (14,114) and said at least one rear foot unit (15,115), and actuation rods of the joining device are provided, arranged in said at least one rear foot unit (15,115), positioned between said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) and wherein: - said connection group of the joining device of each front foot unit and rear foot unit comprises a pin, for positioning integrally in a shoulder, and said blocking group of the joining device comprises a grub screw which can be moved from an engagement position to a disengagement position with said pin, the grub screw of the rear foot unit having an actuation point in the rear foot unit and the actuation rod of said blocking group of said rear foot unit having an actuation point in the front foot unit, said actuation rod of said blocking group of said rear foot units is positioned tilted on a plane perpendicular to the floor between said at least one front foot unit (14,114) and said at least one rear foot unit (15,115), characterized in that - said actuation point of the grub screw in the rear foot unit and said actuation point of the actuation rod in the front foot unit are, when the joining and levelling system is mounted to a piece of furniture standing on a floor, not positioned in the same plane parallel to said floor. the furniture, said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) are suitable for being positioned beneath said bottom and facing said at least one shoulder, wherein said bottom and said at least one shoulder do not rest on the floor, said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) are positioned in an identical body (16,116) for both said at least one front foot unit (14,114) and said at least one rear foot unit (15,115), and actuation rods of the joining device are provided, arranged in said at least one rear foot unit (15,115), positioned between said at least one front foot unit (14,114) and said at least one rear foot unit (15,115) and wherein: - said connection group of the joining device of each front foot unit and rear foot unit comprises a pin, for positioning integrally in a shoulder, and said blocking group of the joining device comprises a grub screw which can be moved from an engagement position to a disengagement position with said pin, - said connection group of the joining device of each front foot unit and rear foot unit comprises a pin, for positioning integrally in a shoulder, and said blocking group of the joining device comprises a grub screw which can be moved from an engagement position to a disengagement position with said pin, the grub screw of the rear foot unit having an actuation point in the rear foot unit and the actuation rod of said blocking group of said rear foot unit having an actuation point in the front foot unit, said actuation rod of said blocking group of said rear foot units is positioned tilted on a plane perpendicular to the floor between said at least one front foot unit (14,114) and said at least one rear foot unit (15,115), characterized in that - said actuation point of the grub screw in the rear foot unit and said actuation point of the actuation rod in the front foot unit are, when the joining and levelling system is mounted to a piece of furniture standing on a floor, not positioned in the same plane parallel to said floor. - said actuation point of the grub screw in the rear foot unit and said actuation point of the actuation rod in the front foot unit are, when the joining and levelling system is mounted to a piece of furniture standing on a floor, not positioned in the same plane parallel to said floor.