This study investigated the effects of an intensive summer program on students' writing, reading, listening, vocabulary, and grammar skills. The program consisted of 4 weeks at the U.S. home institution and 4 weeks in Berlin, Germany, and offered the equivalent of two college-level, second-year German classes in one summer. During the last three summers, students' language skills were assessed before and after each summer program using the DIALANG assessment tool. Data were also collected from students participating in the regular-semester classes, and the outcomes of students in fourth-semester German were compared to those of students in the summer program. Data revealed that the summer students made statistically significant improvements in all language areas from before to after the program. They outperformed the students who completed the regular courses at home in the areas of vocabulary and listening but achieved lower levels in reading. The results suggest that intensive summer programs that combine at-home courses and a short-term stay abroad have positive effects on students' second language skills and can provide a viable option for students who are unable to spend longer periods in the target country.