Psychometric and field studies are reported concerning the development and assessment of the Labour Agentry Scale, an instrument measuring expectancies and experiences of personal control during childbirth. Factor analysis yielded evidence that it is a unifactorial scale, with factor loadings between 0.36 and 0.85. Dual-scaling techniques corroborated the results of factor analysis and provided evidence that few differences exist between antepartum and postpartum samples' responses to individual items. Field studies yielded evidence of an inverse relationship between anxiety and control, as well as evidence of construct validity. For example, subjects who had spontaneous, unmedicated births had the highest Labour Agentry Scale scores.