Many developing countries' tourism economies rely heavily on the informal sector. This includes the set of economic activities, often but not exclusively carried out in small firms or by the self-employed, that evade government requirements such as registration, tax and social security obligations, and health and safety regulations, known as informal actors. Both informal and formal players collaborate with one another through mutual trust and shared resources, which has the potential to improve resource utilization and efficiency. This study aims to investigate the impact of cooperative practices on tourism service quality, examine how informal actors influence cooperative practices and service quality, and analyze the role of core competencies among formal actors in shaping tourism service quality and cooperative dynamics. With 165 participants, this quantitative study made use of SPSS and structural equation modelling. We find that firms' core competencies influence tourism service quality, whether through coopetition or direct relations, whereas informal actors' threat influences tourism service quality solely through coopetition. The factors that contribute the most in: 1) core competencies are marketing, finance, and human resource competence; 2) perceived threat of informal actors are market competitiveness, the existence of informal actors, impersonators of informal actors, and price competitiveness; 3) coopetition are market commonality, resource similarity, and willingness to cooperate; and 4) tourism service quality are assurance, responsiveness, and empathy. This research contributes to the strategic management literature by expanding on basic game theory, transactional cost theory, resourcebased theory, dynamic capabilities theory, and social network theory, all of which have the potential to lead to win-win situations and mutual benefits.