This study explored the development and maintenance of intercultural communicative competence (ICC) among 352 American learners of Arabic who completed summer intensive language programs in five Arab countries. Data were collected through a survey that was based on the 2007 draft of the Culture Proficiency Guidelines (Lampe, 2007; later adopted by the Interagency Language Roundtable in 2012) that was designed to measure ICC development and was administered upon students' return to the United States. The survey also investigated which components of the intensive study abroad program fostered the development of particular components of ICC. Data indicated that although students mostly developed ICC at the Intermediate level (completing daily activities), they also progressed into higher levels, e.g., by identifying, comparing, and contrasting traditions, history, and politics or by participating in low-frequency social occasions. Data showed that the structured and the unstructured components of the program and the diglossic learning of Arabic both supported, to various degrees, students' development of ICC. Data also suggested that students sustained their developing levels of ICC upon their return to the United States, as demonstrated by their ability to shift perspectives, their increased compassion toward different populations, and their sensitivity to stereotyping.