Background: In recent years, science curricula (chemistry, physics, biology, earth science, life science, etc.) in many countries have been prepared and applied according to the inquiry-based learning approach. Although the acquisition and application of the inquiry skills are one of the important objectives of the science curriculum, the inquiry skills of each student do not enhance at the same level. The inquiry level of the learning environment; the importance and value attached to the inquiry in that environment, students who have different goals when attending to the learning environments, and students who do not get involved in the learning process at the same level can be shown as the reasons of this. Purpose: The purpose of this research is to examine both the direct and indirect relationships between the inquiry-based self-efficacy, the achievement goal orientation, the learning strategies, and the inquiry skills variables. Sample: This research was conducted during the 2015-2016 school year among 498 seventh and eighth graders at public schools in Turkey's Aydin province. Design and methods: The Inquiry-based Self-Efficacy Scale, the Goal Orientation Scale, the Learning Approach Scale, and the Inquiry Skills Test were applied to the students. The analysis of data was carried out through the Multilevel Structural Equation Model (MSEM). Results: The findings related to the first model did not provide evidence for either direct or indirect effects of the inquiry-based self-efficacy on inquiry skills, achievement goal orientation, and learning strategies. However, findings from the final models provided evidence for both direct and indirect effects of separately inquiry-based self-efficacy and the achievement goal orientation on the inquiry skills through the learning strategies. Conclusions: This study demonstrates the potential that relations with self-efficacy, achievement goal orientation, and task value theory while improving inquiry skills. (Includes questionnaire.) [This paper was presented at the National Congress of Science and Mathematics Education (12th, Trabzon, Turkey, September 28-30, 2016.]