Conversion is one of the ways in which religion diffuses in society. Different than other diffusions, such as adopting a new technology or a fad, religious adoption can be riskier since it entails a life changing transition thereby making it a complex contagion. This study investigates whether Islam diffuses through weak ties or strong ties. By comparing conversion cases in Michigan, where there is a larger Muslim community, and Kentucky, where there is a less tangible Muslim community, I argue Islam is more likely to diffuse through what I call recessive or dominant weak ties in Michigan, whereas it is more likely to diffuse through strong ties in Kentucky. I collected personal social networks of 18 individuals who converted to Islam living in Michigan and 12 living in Kentucky. I found the research participants through mosques located in several cities in Michigan, including Ann Arbor, Ypsilanti, Flint, Detroit, Dearborn, and Canton, and two cities in Kentucky: Lexington and Louisville. Having investigated a set of egocentric conversion networks from both Michigan and Kentucky, I found that the existence of a Muslim community and how it is perceived by mainstream society is an ultimate factor in determining the strength of a tie to other Muslims. Thus, Islam is more likely to diffuse through weak ties where there is a Muslim community, but it is more likely to diffuse through strong ties where there is no such community.