The present study seeks to develop a pedagogy aimed at fostering a student's ability to reason causally about history. The Model of Domain Learning was used as a framework to align domain-specific content with pedagogical principles. Developing causal historical reasoning was conceptualized as a multidimensional process, in which knowledge of first- and second-order concepts, strategies, epistemological beliefs and interest play a role. Five pedagogical principles (inquiry tasks, social interaction, situational interest, explicit teaching of domain-specific strategies and concepts, and epistemological reflection) were established and operationalized for causal historical reasoning. The effectiveness of the principles was explored in a lesson-unit concerning the outbreak of the First World War. A quasi-experimental pre-test--post-test study was conducted with two conditions in three 11th grade pre-university classrooms. Students in the "implicit condition" worked in triads on the inquiry task. Students in the "explicit condition" worked on the same task, but with explicit attention given to strategies, concepts and epistemological underpinnings. The results showed that first-order knowledge increased in both conditions, but students in the explicit condition acquired significantly more knowledge of second-order concepts and causal strategies. However, no differences were found in students' written explanations. Several possible reasons for this are discussed.