To develop computational thinking (CT), a variety of programming environments can be selected from. Apart from a focus on developing specific skills, flanking pedagogical conditions can play an equally important role. The aim of our study is therefore to investigate, among ninety upper grades primary school students in Belgium, the effect of learning to program in a visual programming environment on the development of CT, and to what extent this effect is influenced by self-regulatory ability. To investigate this, a quantitative quasi-experimental research design was adopted using two intervention groups that applied either a visual programming environment with tangible output or a visual programming environment with on-screen output. To determine the difference in the development of CT and the influence of self-regulatory ability, a pretest-posttest design was used. Our initial indications show that significant differences in CT development are noticeable between the two programming environments, but that learners' self-regulatory ability had a weak but no significant impact on the development of CT. Based on the results obtained, it is recommended to further investigate the importance that can be attributed to regulating thoughts, feelings, abilities and behaviour, and that cooperating with the environment and handling feedback when developing CT are essential prerequisites.