Semantic priming was analysed in two groups of French children contrasted on comprehension skills with a visual lexical-decision task using a long SOA (800 ms). Two relation types between related primes and targets were examined: pure semantic relation (categorical vs. functional), and lexical association strength (strong vs. weak). Targets were preceded by related, unrelated, and neutral primes. Skilled comprehenders showed semantic priming only for category-related words, whatever their association strength, and without any evidence of an associative boost. Less-skilled comprehenders also showed semantic priming for category-related words, irrespective of their association strength, but with an indication of an associative boost. They also displayed semantic priming for function-related awords that are strongly associated, but not for those that are weakly associated. These results are discussed within the theoretical frame proposed by Plaut and Booth (2000).