PurposeThe development of mass-customization capability (MCC) is crucial for a growing number of manufacturing firms nowadays and presents great challenges, especially in the area of operations management. The purpose of this paper is to provide insights into which individual competencies (ICs) of an operations manager (OM) are important to the MCC of the manufacturing organization the OM works for.Design/methodology/approachA multiple-case study was designed, involving eight machinery manufacturers in one European country, to collect data on their MCC and on the ICs of their OMs. Empirical case data were triangulated with analytical conceptual arguments grounded in the existing literature.FindingsThe study provides empirical evidence of, and logical explanations for, the fact that OMs working in high-MCC manufacturing organizations use the ICs of negotiation, information seeking, efficiency orientation, analytical thinking and pattern recognition significantly more often than OMs employed by low-MCC organizations.Research limitations/implicationsFuture research could replicate this study in other industries and countries, as well as for other managerial roles.Practical implicationsThe study provides indications for OM selection and training in companies that are pursuing a mass-customization strategy.Originality/valueWhile the literature on technological and organization-level enablers of MCC has grown considerably, the understanding of its individual-level enablers is still limited and concerns mostly the workforce. This is the first study that relies not on practitioners’ opinions, but on data regarding manufacturers’ MCC and their managers’ ICs to shed light on which managerial competencies are important to a manufacturer’s MCC.