Raman scattering has been used to investigate strained InAs islands grown on InP(001), in correlation with transmission electron microscopy. Symmetry arguments, selective resonance at the InAsE1‐like transition and comparison with a single‐quantum‐well structure allowed to distinguish between the islands and remaining wetting layer signals. Whereas the vibrational modes of the 2D thin layers are greatly affected by interface roughness and confinement, strain effects mainly account for the phonon frequency shifts in the islands. ©1996 American Institute of Physics.