AbstractFactor analysis of a number of Certificate of Secondary Education (CSE) examinations showed that tests of practical biology loaded significantly on the same factor as biology theory papers. When a fictitious correlation matrix was factored it was necessary for the correlation between tests of practical and theoretical biology to fall to about 0.17 before the two separate tests of biological ability appeared as distinct constructs. It is concluded that the examinations studied were not adequately distinguishing practical biology from theoretical biology. All assessments appeared to be testing a general factor which might be related either to general ability, or to a specific biological ability.