Listeria monocytogenes is a ubiquitous bacterium widely found in the environment; it is transmitted to humans through the ingestion of contaminated food and causes rare but serious cases of illness in humans. This situation justifies the implementation of surveillance for the bacterium in the main processing sectors for meat, dairy, seafood, and plant-based products. These sectors constitute the primary sources of food contamination, particularly in food production, either from raw materials or from the environment where strains can become resident. Recent national surveillance and control plans have made it possible to target the processing sectors most at risk. The comprehensive measures implemented by the food industry and authorities, both in terms of surveillance and management in cases of non-compliance, contribute to controlling contamination and reducing public exposure. Furthermore, characterization analyses of strains isolated from food enable molecular surveillance of the populations of strains circulating in these sectors, allow for the potential identification of contaminated food, and also provide additional information for the epidemiological investigation of cases and, more generally, for risk assessment. (R.A.)