The study investigated how explicit instruction of argumentation-in the context of socioscientific issues (SSI)- and explicit instruction of NOS, compared with explicit instruction of argumentation only, can develop grade 10 students' argumentation skills and NOS conceptions. Participants were 36 grade 10 students enrolled in two sections that were randomly assigned into two groups: Treatment and Comparison. The treatment lasted for 4 months and involved two units about autotrophy and the nervous system. Both the Treatment and Comparison group participants received explicit instruction of argumentation -in the context of SSI. Yet, the Treatment group participants experienced explicit instruction of NOS. To assess participants' argumentation skills and NOS conceptions, they were pre- and post-tested using two open-ended questionnaires as well as individual semi-structured interviews. Results indicated that there were improvements related to the learning of argumentation skills for participants in both the Treatment and Comparison groups, who experienced explicit argumentation instruction. Yet, the degree of improvement varied between the two groups, favoring the Treatment group. Results also showed developments in the NOS conceptions of the Treatment group participants who experienced explicit instruction of NOS and argumentation. These results were interpreted along the following themes: instruction of argumentation, instruction of NOS, and coupling of instruction for argumentation and NOS.