This study examined the development and maintenance of intercultural communicative competence (ICC) among 352 American learners of Arabic who completed three summer intensive language programs in five Arab countries during 2010-2012. Data were collected through a post-program survey based on guidelines drafted in 2007 and later adopted by ILR in 2012. The survey was designed and administered upon return to the United States to measure ICC development. The data indicated that although students mostly gained ICC at the Intermediate level, they also showed ICC progress at higher levels. Moreover, data showed that structured and unstructured components of the program supported the improvement of ICC to various degrees and revealed that diglossic language development functioned as a valuable gateway for developing ICC. An additional open-ended question explored students’ behavior upon their return to the U.S. and revealed sustained ICC in a variety of areas of life and towards different social groups.