What is the developmental trajectory of language-mediated abstraction skills, and to what extent are these skills influenced by semantics? We address these questions asking children to generate semantic relations of categorical inclusion for words varying in concreteness. Results show that abstraction improves over time, independent of age, with both concrete and abstract concepts organized into hierarchical taxonomies. However, abstract concepts allow shorter ladders, making them harder to categorize, especially for younger children. These findings underscore the distinction between concreteness and specificity as separate dimensions of abstract reasoning, and they lend empirical support to theoretical models that treat these facets of abstraction as dissociable.