Modern biotechnology will have a large impact on society and requires informed decision-making and critical attitudes toward biotechnology among the public. This study aims to explore these attitudes in secondary education. For this purpose, a questionnaire was constructed according to the general tripartite theory of attitudes. A total of 574 Dutch secondary school students completed the questionnaire. Based on principal component analyses, several distinct and independent cognitive, affective, and behavioural factors were found, demonstrating that attitudes towards biotechnology are a multi-component concept. In a cluster analysis on these factors, we found four interpretable clusters representing different groups of students. The four groups are labelled "confident supporter" (22%), "not sure" (42%), "concerned sceptic" (18%), and "not for me" (17%). These results indicate that there is a diverse appraisal of modern biotechnology among secondary school students. Suggestions for educational interventions are made. (Contains 1 table, 1 figure and 3 notes.)