Recent immigration in Europe has created a unique situation in Spain. In the last 100 years about 3.5 million Spaniards emigrated to Latin American countries and other European countries such as Germany. Spain has gone from a sender country to a receiver country. Martí Romermo (2015):Between 2002 and 2014, Spain received an accumulated immigration inflow of 7.3 million and a net flow of 4.1 million, making it the second-largest recipient of immigrants in absolute terms among OECD countries, following the United States. According to Eurostat data, 1 out of 5 migrants that moved to the EU during 2002 and 2013 went to Spain.” Coposescu, Caruana, & Scaglione (2013) state that immigrant students in Spain have a hard time acclimating to their communities and schools due to the lack of cultural awareness. Lucas (2002) mentions that 9 out of 10 immigrants in the Madrid region come from countries that are underdeveloped and lack the resources to succeed in the Spanish school system. He suggests that there need to be more opportunities for students to integrate into their classroom by creating more opportunities both inside and outside of the classroom, which will hopefully not only change the school system but the attitude of the communities.Relaño Pastor (2011) corroborates the hegemony of English in CLIL and the lack of mutual understanding with other language learning programs such as the Spanish immersion program at this particular school, which results in the establishment of a distinctive linguistic hierarchy with Spanish at the top as the dominant language immigrant origin students have to learn, followed by English as the most important foreign language at school, and the languages spoken by immigrant-origin students trailing at the end. 2. 2 BENEFITS AND CHALLENGES OF CLILCLIL has been implemented and studied widely since its conception (Marsh 1994), with most of the literature in agreement that the program has numerous benefits. The main benefits we want to highlight are that they connect and relate the language with real life, which means that the students can apply it to their future. Learning through CLIL is engaging and motivating by learning language through context which enhances the teaching-learning process because it allows students to be fully immersed in the lessons. Berton (2008) points out that when students use the language in a real context, they are developing their linguistic and communicative competences. He also adds that it gives the student a significant knowledge of the L2 and gives them vocabulary to deal with practical topics they can use outside a classroom.Warburton (2017) found that the CLIL method implemented in Valencia (a region where two languages are co-official as L1) discovered that the oral communicative competence improved through CLIL programs because students were able to find meaning when they used their L2 to communicate: The annotations collected by the observers, the interest in completing the tasks and the high degree of participation in all the activities show that the initial motivation has varying satisfactorily during the process followed. (p.235)Despite these advantages, researchers have also found disadvantages in CLIL programs. Although it is beneficial when students acquire and learn an L2, it is problematic when teaching. According to Pena (2014), the major problem is that parents are very interested in bilingual schools but these settings have tried create a curriculum that emphasises teaching an L2 without making substantial changes to their pedagogy or materials. There are some issues related to CLIL and they are related to the lack of training of teachers, because not all of them are prepared to effectively implement CLIL. The consequences are quite obvious: children won’t acquire a good command of the L2 if their teachers are not fully prepared.Mehisto, Marsh & Frigols (2009: 21) also pointed out a lack of skills and preparation of the teachers to implement CLIL: “…even if they have the prerequisite skills, not all teachers are prepared to focus on content and language goals”. The challenges of CLIL methods are mainly related to the teachers’ preparation and materials:One of the challenges faced by the language teacher is lack of expertise both in content areas and in the discipline-specific pedagogy within which language teaching is fixed. They must develop their knowledge of content vocabulary and its pronunciation. The most of important challenges is to find appropriate material for content classes. In CLIL approach, the assessment generally complicated for the teachers whether to assess content, language or both. Most of the teachers are not familiar with the implementation of CLIL. (Kondal & Bairi, 2017, para. 13)2. 3 BILINGUAL PROGRAMS AND IMMIGRATIONAccording to Parmon (2010), “There is no evidence that bilingual education hinders the process of an immigrant child learning English, and bilingual education actually can provide advantages such as enhancing cognitive thinking skills.” (Parmon, 2010, 68) Many researchers studying bilingual schools with programs such as immersion or two-way dual language agree; they find similar academic and cognitive benefits.However, most of these studies were carried out in the United States and examined immigrant students who were educated in a program where they spoke one of the two languages. The research on the benefits where the students already know one of the two languages overwhelming favors bilingual programs. These studies demonstrate the myriad benefits of bilingual education. There are many studies looking at students in either Spanish/English or Chinese/English bilingual programs. The students enrolled in these programs speak one of the two languages at home. Chin (2015), Biling Res (2013), and Williams Fortune (2012) all elucidate the benefits of dual language programs on academic achievement, especially for immigrant students. They highlight that these programs improve test scores and do not hinder immigrants’ acquisition of English, the majority language. Marian & Shook (2012) summarize the findings of many studies on the benefits of bilingualism, where many authors agree that speaking two languages helps cognitive function and memory. However, even Parmon (2010), which focuses specifically on immigrants in bilingual schools, only studies populations where the students’ L1 is one of the languages included in the program. There are no mentions of immigrant students who speak a different language enrolling in such a dual language program, although it is highly likely these students exist in the chosen population.Relaño Pastor (2014) is of the few authors that analyzes all of these elements: benefits of bilingualism, CLIL, and immigrant students in Spain. She elaborates how the CLIL policies create a hierarchy of language, with Spanish at the top and English as a valuable commodity, while sidelining the importance of the home languages of immigrant students in Madrid. While she touches on how immigrant students perform in CLIL classrooms in Madrid and the psychological effects of social or linguistic isolation, she does not collect specific data on the acquisition of Spanish amongst the immigrant students involved in her study. Many immigrants students mentioned in her case study are immigrants from Latin America who already speak Spanish, and immigrants with other home languages are not discussed.3. METHODOLOGYFor our research we designed a quantitative, longitudinal study. We began with two schools, both with significant populations of immigrants. One school is a traditional Spanish school, with all subjects taught in Spanish (except for English as a Foreign Language). The other school is a Spanish bilingual school employing CLIL, where Science, Art, and EFL are taught in English. Our sample was chosen through non-probability sampling, as we had a very specific set of criteria for our population. We tested students between 9 and 10 years old. For our experimental group, we chose immigrant students that had been in Spain between two and three years, omitting any immigrant students in Spain less than two years or longer than three years. For our control group, we tested the native Spanish-speaking students in the same classes as our immigrant students.Our investigation tools were a pre-test and post-test. We administered a battery of tests to the immigrant and native-Spanish students to assess their proficiency in both English and Spanish. The first test was an Oral Language Inventory, where the administrator says a sentence, and the student must repeat it correctly. There are fifteen sentences, increasing in difficulty. Number and type of errors were recorded and the students were marked on a 15-point scale, determining the student’s level of fluency. (See Appendix 1) The second test involved reading a short story, answering 5 multiple choice questions, and 2 open-ended questions. (See Appendix 2) All tests were administered in English and Spanish. All the tests dealt with BICS (Basic Interpersonal Communication Skills), not CALP (Cognitive Academic Language Proficiency). We chose to focus on BICS because it typically takes 2 years from arrival for an immigrant student to develop these skills in a full immersion context, whereas CALP takes about 5 years. It is also difficult for students not in CLIL programs to develop CALP in the second or third language (English). (Roldan Tapia, 2012)As this was a longitudinal study, we gave these tests 3 times over the course of the year: once in September, once in December, and once in May. This allowed us to observe how significantly the immigrants students’ Spanish skills improved, as well as see the rate of improvement as compared to the native Spanish speakers. We did not suggest any changes or make recommendations for the teachers; we simply wanted to observe the results when the teachers conducted their classes as normal. We then compared the different groups. We compared the immigrant students’ levels of Spanish in each school. We used the results of the native Spanish speakers as a control for the average level of Spanish language and comprehension. We also compared the immigrant students’ levels of English to see if they were acquiring English faster or slower than they acquired Spanish, and to see how their English acquisition compared to that of their Spanish peers.