The study aimed to investigate the spelling performance and the semantic understanding of compound words by 103 Greek primary school children (first through sixth grade). The experimental group comprised of 25 children with spelling difficulties and compared with a control group of 78 children of typical development. Children were asked to spell and define 20 concrete and abstract compounds. They were also asked to spell 20 different compounds after providing their definitions in terms of their morphological constituents. Main results indicated that concrete compounds were spelled and defined better than abstract ones, but the experimental group performed significantly lower than the control group on both word types. Children with spelling disabilities were able to use less etymological information in defining compound words than their typical classmates, suggesting that they understand less the internal structure of morphologically complex words. These results are compatible with the experimental literature and are discussed in terms of the morphophonemic nature of Greek language as a transparent orthography with a rich morphology. (Contains 5 notes, 5 tables, and 1 figure.)