Inference is considered an important factor in comprehension models and has been described as a causal factor in predicting comprehension. To date, specific tests for inference are rare and often rely on specific thematic texts. This reliance on thematic inference may raise some concerns as inference is related to prior text-specific knowledge. The Riddle Knowledge Inference Test consists of 14 riddles written in French with different specific topics for each item and was administered to 565 participants in a longitudinal study from grade 2 to grade 5. Both classical test theory and item response theory provide evidence of reliability, with a one-factor solution of [omega subscript t] = 0.860 and metric invariance for gender and social background. However, due to the large differences in the level of latent scores between participants, it was not possible to establish a standard setting for each grade.