A sliding and positioning device for a piece of furniture or the like comprising at least one main door and at least one secondary door, the sliding and positioning device comprising at least one first opening device which can be fixed, on one side, to the piece of furniture and on the other side to the internal face of each door (AC, AL), wherein said first opening device comprises at least one first guide means, which is elongated, having longitudinal extension nearly equal to the overall width of the doors (AC, AL) in the condition of complete closing of the piece of furniture and parallel to the geometric plane defined by such doors (AC, AL) in said condition and parallel to the main opening and closing direction of the doors (AC, AL); said sliding and positioning device further comprising for each main door a respective moving means of the at least one first opening device for fixing the corresponding main door to said at least one first opening device, each moving means having a primary carriage means which slides along first rail means which extend along the first guide means parallel with it and carrying a secondary carriage means slidably connected to the primary carriage means in a leaving and approaching direction of the respective main door from and to the first rail means, said leaving and approaching direction being perpendicular to the first rail means and to said closing geometric plane; wherein said sliding and positioning device comprises for each secondary door a respective rolling means of the at least one first opening device for fixing the corresponding secondary door to said at least one first opening device, each rolling means slides along second rail means which extend along the first guide means parallel with it; characterized in that said device comprises, for each secondary door, a respective enlongated transmission means which slides in a respective longitudinal seat of the first guide means, and which can be connected, at one of its ends, to the respective secondary door by means of a corresponding detachable connection of a kind that is detachable in operation and, at the other end to operation means of the secondary carriage means, wherein the operation means transmit an orthogonally deviated portion of the sliding motion of the transmission means to the secondary carriage means; starting from the total closing condition, the sliding of the secondary door towards the air adjacent main door causes the detachable connection to trail the transmission means, wherein the sliding of the transmission means drives the operation means of the secondary carriage means which displace the main door moving it away from said closing geometric plane allowing the overlapping of the main door with the secondary door and allowing to open the secondary door; wherein the operation means of the secondary carriage means comprise first inclined planes each one fixed to the end of the transmission means such end opposed to the respective detachable connections and acting on a respective wheel means fixed to the secondary carriage means; the initial opening sliding of a secondary door translates the respective transmission means whose first inclined plane acts on the wheel means translating said main door perpendicular to itself and to said closing geometric plane.