This study makes use of a constructivist epistemological stance (in particular that of George Kelly) to explore the . many conceptions young people develop for four concepts in school science - energy, force, heat and light. The work is placed within a growing area of research into students' alternative conceptual frameworks and by adopting a broad, actionable, notion of a concept it is possible to explore the beliefs and contingencies that pervade these youngsters' personal theories. The central methodology involved is an individual interview approach framed around a set of line drawings depicting various situations which the students are asked to discuss in terms of their own conceptions. The interview sessions are conducted in schoo~and are audiorecorded. The four concepts are treated separately across three age bands and the resulting four-by-three, twelve cell, matrix lays the pattern for the analysis and d~scussion of data. Three levels of analysis are discussed which are conceptions, categories of response and frameworks, and these are used as a means of examining the transcript data for some 134 interviews. The relatic1nships betwaen the frameworks are considered and some emphasis is given to the degree of overlap that occurs in the students' use of the four main concepts. The responses of four particular students are explored across all four concepts and the resulting four-by-four, sixteen cell, matrix allows a study of their personalised approach to these ideas in further detail. The methodological checks employed are evaluated and, finally, summaries of the outcomesof the study are made, implications for current practices in science education are drawn and future trends for research are indicated.