A ‘Women’s Crop Tool’ was developed to measure women’s control over decision-making for crop production, sales, and use of income. The tool for groundnuts in Eastern Province, Zambia, was tested using a mixed methods approach that involved Focus Group Discussions (FGDs) and a quantitative household survey. Women in FGDs reported higher levels of control than women in the household survey. The more extreme results from the FGDs are due to the nature of the research question over the ‘power to name’. FGDs provided a public space for a struggle over meaning that exposed latent conflicts over gender roles, gender identities, and the conjugal contract. Mechanization of groundnut shelling increased male participation in this activity. Propensity Score Matching (PSM) was used to determine whether the introduction of shelling machines reduced women’s control over groundnuts, as measured by the weighted women’s gender control index (WGCI), constructed by aggregating the scores obtained from the Women’s Crop Tool. Results showed that the shelling machine significantly increased the women’s WGCI, while the area planted to groundnuts and the volume of groundnut sales had no significant effect on the women’s WGCI. Contrary to the conventional wisdom, therefore, the commercialization of groundnuts has not reduced women’s control over groundnuts, while women perceived that the introduction of the machine sheller had increased their control over decision-making.