The research aim was to examine the effects of a Critique-Driven Inquiry (CDI) intervention on primary and secondary school students' critical thinking and scientific inquiry competency. Twenty-five 4th grade Taiwanese students from a typical primary school were selected to participate in experimental group 1 (EG1), while 28 7th grade students from a typical secondary school were randomly selected to participate in experimental group 2 (EG2). For each group, a 2-semester CDI intervention was implemented. In addition, another 28 4th graders and 30 7th graders from the same two schools were selected to participate in, respectively, control group 1 (CG1) or control group 2 (CG2). Analyses of covariance, repeated measures analysis of variance, and content theme analyses were conducted to analyze the quantitative and qualitative data. Research results indicated that EG1 and EG2 students significantly outperformed their comparison counterparts in critical thinking and scientific inquiry competency both during and following the CDI intervention. The empirical evidence provides insight into the mechanisms of promoting primary and secondary school students' critical thinking and scientific inquiry competency.