The force concept in physics is known to be poorly understood by high school and university students throughout the world, with alternative conceptions being prevalent. In this study, I surveyed the conceptions regarding force of a large and varied convenience sample of South African physical sciences teachers, and sought patterns between levels of understanding and various characteristics about the teachers and the schools at which they teach. Data were collected during teacher-education workshops held throughout South Africa from 1,190 physical sciences teachers, and consist of responses to a seven-item multiple choice test about force and a survey about the teachers and their schools. The findings confirm a high prevalence of force alternative conception, particularly for the impetus alternative conception, and particularly among less experienced teachers. Having a BSc degree was found to be associated with teachers having better understandings of force, except for teachers teaching at quintile 1 and 2 (poorer) schools. The findings tentatively suggest that having a BSc degree might predispose a teacher to be able to benefit, in development of their conceptual understanding, from the advantages which teaching at a higher quintile school offers. This study highlights the need for interventions aimed at improving teachers' understandings of physical sciences concepts as well as their scientific skills, attitudes and values.