We study the growth of (In, Ga)As on GaAs(3 1 1)A substrates by molecular-beam epitaxy (MBE). When the (In,Ga)As layer thickness exceeds a certain value, wire-like structures with widths of several 10 nm develop during growth, due to the strain-driven growth instability. The properties of the nonplanar surface are modulated by the wire formation, resulting, upon further (In,Ga)As growth, in islands nucleation exactly on top of the wires. A surface layer of floating In built up by segregation is assumed to be the driving force for the island formation. The MBE growth of (In,Ga)As on GaAs(3 1 1)A, thus, reveals two distinct growth behaviours which might be generic in the deposition of thin low-misfit films. (C) 2002 Elsevier Science B.V. All rights reserved.