The research reported in this thesis arose from a comment made by a student who had achieved highly in examinations yet felt that science: ‘doesn’t make sense’. Different conceptualisations of learning are analysed leading to the development of the concept of making sense as the formation or modification of a conceptual compound in which concepts are related in a coherent causal system that may be transferred to novel situations. This definition is situated within a constructivist epistemology. The research question asks how students make sense of physics concepts in dynamics and electricity. Five 17-18 year-old students, conceptualised as a multiple case study, were selected from an English secondary school using purposeful sampling. The students were interviewed once a week for 22 weeks in sessions using a range of probes such as interviews about instances, concept maps and concept inventory questions. It is assumed that data collection occurred at a frequency that was high relative to the rate of conceptual change, hence, the work is conceptulaised as microgenetic. The analysis focuses on the development of the students’: a) ontologies of concepts from concrete instances towards abstractions; b) conceptual structures from temporary organisations to more stable structures; c) understanding of causality from focused on macroscopic objects to abstract concepts; d) judgments of coherence; f) conceptual change modeled as an alteration in the ‘oftenness’ of application of a concept in a given context; and e) ability to apply concepts to novel contexts. The implications of these findings for teaching and future research are discussed.