Despite the increasing global mobility in higher education, international students in the United States and Japan face persistent challenges in well-being and inclusion. This study investigates international students' experiences of loneliness and their social engagement in a comparative perspective, focusing on friendships and involvement with volunteer organizations as the participants' most prominent types of social involvement. Utilizing qualitative data from in-depth interviews with 15 international students conducted during the coronavirus disease (COVID-19) pandemic, this research identifies the limited friendships with domestic students and the underutilized potential of volunteer organizations as key issues. The findings suggest better coordination with external stakeholders to enhance support systems. The study concludes that universities alone cannot address these challenges and recommends fostering collaborations with community organizations to improve international students' social integration and well-being.