Critical questioning is crucial for being able to successfully construct knowledge within collaborative argumentation on science-related issues. Regrettably, laypeople often lack the required skills and intrinsic motivation to do so. In a 1 × 2 between-subjects design (training vs. no training), the present study investigated if training the members of a dyad on critical questioning individually promotes their critical questioning behavior in discourse and their subsequent argumentation behavior. Results of content analyses show corresponding beneficial effects of the training. Furthermore, analyses revealed a marginal positive effect of the training on general critical thinking scores. The training also succeeded in ensuring students’ intrinsic motivation. Implications for developing further trainings to promote critical argumentation and critical thinking are discussed.