Cultural intelligence (CQ), defined as ‘an individual’s ability to be effective in situations characterized by cultural diversity’ (Ang, Van Dyne, 2008), can be developed and strengthened through experience, education and training. Field research has demonstrated that living and working abroad can contribute to ‘training’ culturally intelligent individuals (Ang, Van Dyne, 2008). More specifically, the role of traineeships abroad in developing cultural intelligence has already been investigated through the analysis of more than a hundred trainees’ field journals. The findings clearly confirmed the positive relation between a traineeship abroad and the development of CQ. Good linguistic skills, or at least motivation and attitude to develop them, was identified as a key factor, together with the availability of cultural training to increase awareness, motivation and knowledge of the host country, the essential ‘bricks’ of cultural intelligence (Zanazzi, 2010). This paper focuses, instead, on a different type of experience abroad: volunteering, or service learning, as it is often referred to in academic programs. The analysis is based on field journals written by American college students engaging in a service learning program during their study abroad in Italy, between 2011 and 2016. In our work, we use the grounded theory (Glaser & Strauss, 1967) as a methodological approach to qualitative research, where theory is rooted in the data and emerges from it. From the contents of more than 200 field journals, direct observation during seminars, feedback from supervisors and periodic informal talks with volunteers, several themes emerge that can be referred to the cognitive, meta-cognitive, motivational and behavioral dimension of cultural intelligence, showing how service learning abroad can become a fertile ground for cultivating this crucial ability.