This thesis contributes to the scholarly understanding of Nahdlatul Ulama (NU) and Muhammadiyah and the role these Muslim organisations perform in the political socialisation of Islam through their affiliated pesantren (Islamic boarding schools). The study has a regional focus, concentrating on two case studies, both in Lamongan, East Java; Pesantren Sunan Drajat represents the NU pesantren system, and Pesantren Karangasem portraying the Muhammadiyah version of pesantren. Bourdieu&rsquo;s concepts regarding habitus, field, symbolic capital, symbolic power, and symbolic violence are used to examine the pesantren system and the way it reproduces socio-religious identity through the values that santri (students) acquire. Moreover, this study looks at how pesantren and their kyai (headmasters) have influenced the political culture of the umat (religious community). Participant observation provided a detailed insight into the pesantren system, which was complemented with empirical data from election results and a survey to assess the voting habits of Lamongan residents.The development of political Islam in Lamongan is tied to the history of Islam and the strong pesantren culture in the district. This resulted in the popularity of the Islamic political parties and parties that promote Muslim identity, including Masyumi and the NU party at the 1955 general election; the United Development Party (Partai Persatuan Pembangunan, PPP) during the Suharto regime (1966-1998); and the National Awakening Party (Partai Kebangkitan Bangsa, PKB) and National Mandate Party (Partai Amanat Nasional, PAN) in the post-Suharto era. Pesantren Sunan Drajat educates its santri to be obedient, and its headmaster demands the community faithful follow his guidance in supporting political candidates that defend the interests of NU. Pesantren Karangasem on the other hand teaches its santri to think critically, but the school&rsquo;s educators encourage their followers to support cadres that represent the Muhammadiyah constituency. Although people consider the opinions of their local kyai, people are not subservient to their political instructions. Despite this, NU and Muhammadiyah identity remains a salient influence on voters in Lamongan. However, political disunity among NU figures has increased the electoral appeal of the Muhammadiyah candidates, particularly in elections for district head (pemilihan kepala daerah, Pilkada)