This paper explores the first decade of Kellogg’s Corn Flakes on the Swedish market (1929–1939), critically examining its national marketing campaign through van Leeuwen’s model of legitimation. It argues that scientific motherhood was a core aspect of Kellogg’s campaign, with advertisements emphasising three key themes: The Dutiful Mother and Wife; The Importance of Good Health; and The Embracing of Modernity. Through their advertisements, Kellogg’s urged mothers to break old breakfast habits and switch to Corn Flakes to ‘protect’ their children, emphasising the product’s health benefits. They also drew attention to the convenience and versatility of Corn Flakes, making it ideal for modern life. The campaign was highly effective, both shaping mothers’ understanding of cereal and turning it into a core part of Swedish breakfast habits. Central to this success was Kellogg’s careful balance between conveying expert knowledge and transmitting common sense grounded in established social practices. Treading this difficult tightrope served to give mothers a false sense of control over their lives as if they were the knowledge holders with agency to make their own decisions about their families, yet in reality they were being guided by the views of physicians, scientists, grocers and, ultimately, the food industry. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.