A quasi-longitudinal case study was used to determine the effects on secondary students of participation in a program of enrichment and extracurricular science activities in terms of their interest and enjoyment in being involved in science activities, their motivation to continue to participate in science, and their perceptions about scientists and about the role of science in society. Two groups of students in an Australian school were followed simultaneously, a junior cohort through Years 8 to 10 and a senior cohort through Years 10 to 12. Data were collected from 20 students; 5 girls and 5 boys from each cohort. A strong positive relationship was found between changes in students' interest and enjoyment and changes in their motivation, and both these variables increased, in an overall sense for the combined student population, during the study period. All students generally held a high perception of both the normality of scientists and the importance of science in society throughout the study period. Participation in science activities impacted overall positively, but to varying extents for different activities, on all four dependent variables. Suggestions for the structure and/or conduct of competitions, excursions, and practical work, including the design of museum exhibits, and implications for further research are presented. The paper is based on the first author's doctoral dissertation.