We report on the formation of (In,Ga)As self-assembled quantum structures grown on different orientations of GaAs along one side of the stereographic triangle between (100) and (111)A. The samples were characterized by atomic force microscopy. A systematic transition from zero-dimensional (In,Ga)As quantum dots to one-dimensional quantum wires was observed as the substrate was varied along the side of the triangle between (100) and (111)A. An explanation for the role of the substrate in determining the size of the nanostructure is proposed. (c) 2004 Elsevier B.V. All rights reserved.