The participation of Islamic political parties in electoral politics is a rather understudied phenomenon for the simple reason that they are often operating in non-competitive political environments. This study aims to make a contribution to our understanding of democratic participation in Muslim societies, the role of Islamist parties in the democratic process, and the trajectories these parties are likely to take in future. Since 1998, Indonesia has had three cycles of democratic elections, in 1999, 2004, and 2009. Malaysia has had a democratic system since obtaining its independence from the British in 1957. The Islamic Party of Malaysia (PAS) has participated in democratic elections since the early 1960s. In the last three elections, PAS has been a member of the opposition coalition. A leading Indonesian Islamic party, PKS (Partai Keadilan Sejahtera - Prosperous Justice Party) has been a coalition member with President Susilo Bambang's Democratic Party in Indonesia in the last two elections. The paper will answer two broad sets of questions: (1) what adjustments an Islamic party makes as a response to electoral resultst; and (2) what kind of demands and concessions Islamic parties make as a result of participating in coalition politics? Theoretical literature on elections and coalition politics suggests that an ideology-driven political party, such as PKS or PAS, would not sacrifice its ideological stance for the sake of electoral success. On the other hand, such a party would be more willing to alter its ideological posture in order to become a member of a political coalition. The proposed study plans to test this theoretical background against the two case studies of PKS and PAS. The study will include the PKS' and PAS' performance in the last three Indonesian and Malaysian elections (1999, 2004, and 2009). Specifically, I will attempt at answering the following questions: (1) how do PKS and PAS respond to electoral results (the implications of success and failure)?; (2) do they make demands or concessions prior to entering coalition politics?; (3) how do they behave once they enter coalitionsi (how they negotiate?; are they flexible in their demands?); and (4) does participation in coalition politics has a moderating or hardening effect on their ideology? The paper is based on archival research and personal interviews with leading members of PAS and PKS, both of which are conducted in the summers of 2009 and 2010 (planned).