Language-intensive exposure and immersion can be regarded as key factors in developing proficient language learners. In the context of teaching English as a foreign language (EFL), the current research was conducted to compare two modes of teaching English using the "Unlock Textbook Series" published by Cambridge University Press at Birzeit University, Palestine. This research effort aimed at investigating the intensive and non-intensive students' attitudes towards the Unlock Textbook Series in addition to the effectiveness of the intensive and non-intensive modes of teaching based on EFL instructors' perspectives. In a descriptive design, two quantitative instruments were utilized to obtain data; a student questionnaire was implemented with students from the two tracks; intensive and non-intensive, whereas an attitudinal scale was used to examine the effectiveness of the two modes of teaching according to EFL instructors' perspectives. The participating students were (182) non-intensive and (100) intensive students. As for the instructors, fifteen (15) BZU instructors of English participated on the condition of teaching the two tracks. The findings revealed that there were statistically significant differences in the intensive and non-intensive students' attitudes towards the "Unlock Textbook Series" based on students' perspectives in favor of the intensive students. Additionally, it was shown that the intensive mode was more effective than the non-intensive based on instructors' perspectives. Accordingly, some recommendations were suggested.