This book constitutes the refereed proceedings of the 15th International Workshop on Constructive Side-Channel Analysis and Secure Design, COSADE 2024, held in Gardanne, France, during April 9-10, 2024. The 14 full papers included in this book were carefully reviewed and selected from 42 submissions. They were organized in topical sections as follows: Analyses and Tools; Attack Methods; Deep-Learning-Based Side-Channel Attacks; PUF/RNG; and Cryptographic Implementations.