A review is presented of recent work on (1) the origin of the concept of enhanced multiple electron-hole pair (i.e. exciton) production in semiconductor quantum dots (QDs), (2) various experiments based on time-resolved fs to ns spectroscopy (transient IR absorption, transient visible to near-IR bleaching due to state filling, terahertz spectroscopy, and time-resolved photoluminescence) that support the occurrence of highly efficient multiple exciton generation (MEG) in QDs, (3) thermodynamic analyses of the theoretical enhancement of the conversion efficiency in solar cells that are based on MEG in QDs, (4) MEG in QD arrays that can be used in QD solar cells, (5) theoretical models to explain MEG, and (6) some recent controversy about the evidence for MEG. (C) 2008 Elsevier B.V. All rights reserved.