Self-organized vertical and lateral ordering in PbSe/Pb1-xEuxTe quantum-dot superlattices is investigated as a function of PbSe dot layer thickness. An efficient lateral ordering and face centered cubic-like dot stacking occurs only for PbSe thicknesses between 4–6 monolayers. For smaller thicknesses, no correlations are formed, whereas for larger thicknesses the dots are vertically aligned along the growth direction. These transitions are explained by changes in interlayer dot interactions as a function of the dot size. © 2003 American Institute of Physics.