This paper focuses on a training program in inductive reasoning for first-grade students and presents the direct results as well as the longitudinal effects of the evaluation study. The training is based on Klauer's theory of inductive reasoning and on his "Cognitive training for children" concept (Klauer, 1989a). The training program consists of 120 problems which can be solved through inductive reasoning. The tools for the training exercises were selected to correspond with the age of the targeted cohort. The experimental group in the study consisted of 90 students, whereas the control group was made up of 162. An inductive reasoning test was used in the pre- and posttest as well as in the follow-up study (one year later). The test comprised 33 figural, non-verbal items (Cronbach [alpha] = 0.86). On the posttest, the experimental group significantly outperformed the control group by more than one standard deviation. The experimental group scored significantly higher in each skill area targeted by the training. The most noticeable development was found in system formation. No gender differences were detected on the pre- or the posttest. The effect size of the training program was d=1.12. In the follow-up study, the experimental group still significantly outperformed the control group; however, their respective levels of development had not changed in this one-year period. Thus, the training effect proved to be stable over time independent of individual students' original level of inductive reasoning. This study provided evidence that inductive reasoning could be developed very effectively at this early age. (Contains 6 figures and 2 tables.)