In the age of globalization, proficiency in English communication plays a crucial role in police missions. Consequently, the development of appropriate materials and suitable modes of instruction for an ESP course that is based on the specific needs, contexts, and characteristics of Thai Metropolitan police officers is instrumental to the success of their performance of duty. Needs analysis (NA) is inarguably considered a necessary first step in designing ESP courses. However, investigation into the Thai Metropolitan police's needs of communicative English has been lagging. This study therefore aimed at identifying English skills Thai Metropolitan police officers perceived as the most important for their work and the problems they had while communicating in English on duty. Questionnaires were developed and distributed to a group of Metropolitan police officers, and semi-structured interviews were conducted to gather in-depth data. The study found that the participants expressed the needs to develop their general and technical communicative English skills through face-to-face interactions with the instructors, both native and non-native, and their peers. They also agreed that working collaboratively on simulations gave them confidence and equipped them with the kind of language they needed to use on duty. Therefore, it is recommended that policy makers and administrators should provide ESP courses for Metropolitan police, and material developers and ESP instructors ought to include task-specific topics and collaborative, task-based activities that are relevant to the Metropolitan police officers' needs and actual line of work. Responding to their needs should increase engagement in their English training which will ultimately lead to success in their learning, enabling them to fulfill their job responsibilities, increasing their chances of career advancement, and improving satisfaction of those requiring their services.