This thesis presents research studies carried out with upper secondary level physics students (n=14) over a timeframe of four months, with the aim of promoting their conceptual understanding of the electrostatic concepts, Coulomb’s law, electric fields, and work and potential difference. Teaching and learning materials were developed that adopted Inquiry Based Learning (IBL) with structured inquiry tutorials and Multiple Representations (MR) approaches to examine the extent of conceptual change in the student’s understanding of these topics. The research utilizes a case study methodology, with various sources of evidence recorded. These sources include pre-test and post-test comparison, retrieval of student artefacts used during lessons, audio recordings of student’s discussions during lessons, teaching and learning interviews and teacher field notes. In the research design, vector concepts, the inverse square law and field line representations were identified as concepts that students need to be familiar with, to develop their understanding of electrostatics. The students completed structured inquiry tutorials for these topics in the context of mechanics. The findings of these studies show that conceptual change generally occurred in the student’s understanding, for these three concepts, with evidence of conceptual extinction and extension occurring. However, the findings of these studies show students encountered difficulties in transferring their understanding of vectors, the inverse square law and field lines to the electrostatic context. By revisiting these concepts during the electrostatic tutorial lessons, evidence of conceptual exchange and extension was observed in the student’s understanding of Coulomb’s law, the electric field and work and potential difference. The research presents evidence that the use of structured inquiry tutorials and multiple representations can be an effective approach in promoting conceptual change in student’s understanding of electrostatics in upper secondary physics. The overall findings of this research suggest that this approach may have significant benefit for the teaching and learning of other physics / science topics at both upper secondary and lower secondary levels.