The study examines factors which influence primary heads' decisions whether or not to include sex education in the curriculum. This is done using a questionnaire of 83 statements based on factors thought likely to discriminate between heads who support sex education and those who do not. The questionnaire was developed using statements from a small group of primary heads who were asked whether or not they had sex education in their schools and their reasons for this. These statements together with others from the literature were examined and analysed, reduced from a pool of about 170 to the final 83, and presented to a larger group of heads In another area. Influences upon heads' sex education decision-making were identified from the responses to these statements. The study was undertaken in 1990 in The North Kent Area where all 77 heads of all primary schools were invited to contribute. 54 heads did so, (response rate of 70.1%). 26 schools were junior, 28 were Junior mixed and infant. 37 were county schools, 11 Church of England and 6 Roman Catholic. 31 schools included sex education, 21 did not and 2 gave no indi, cation of status. 16 heads were women, 34 were men and 4 remained anonymous. The main hypothesis is that heads are main; y influenced by a few factors from the whole possible range which are said to influence curriculum development, and these will be close to, or within the school, in terms of their strength of influence. These will include factors which are personal to the head, with others relating to the staff and school, parents and families and the head's perception of children's needs and development. Two methods of analysis were applied to the data. The main method was by factor analysis, together with the use of cross-tabulation analysis. These methods combined to identify 33 statements in the questionnaire which discriminated between Sex Education and Ron-Sex Education heads. The main hypothesis was supported, that heads were influenced by factors in or close to the school. Heads regard themselves as occupying a significant position of influence over sex education decisions and expect theirs and the governors' decisions to be the sane. Sex Education Heads were more consistent in responding as anticipated and displayed higher levels of agreement/disagreement with the statements than Non-Sex Education Heads. Non-Sex Education Heads displayed a higher degree of ambivalence and ambiguity in their responses, Sex Education Heads showed greater personal commitment to their position compared with Non-Sex Education Heads. The 33 discriminating statements have been used to form a 'Sex Education Inventory' which could have various applications. It shows that many of the reasons for-against sex education in the literature have little influence on heads' decisions. It identifies those factors which are influential. It informs the sex education debate of the basic factors which need to be addressed to gain heads' support. It provides a means of determining where heads are on the for-against sex education continuum. It gives a sound starting point to those providing training, advice or support for the introduction, implementation and development of primary school sex education. The study provides a conceptual analysis of the factors which influence and shape sex education decisions.