This book is an ethnographic study of migrants, refugees and 'temporary' people in Malaysia,  incorporating narratives, personal stories, and observations of everyday life in Kuala Lumpur and Georgetown, Penang. Rather than focusing on specific migrant communities or refugee 'camps', the book takes subaltern cosmopolitanism as its central lens to look at how different and diverse communities of non-citizen 'pendatang' (aliens) co-habit, work and live together in Malaysia. Urban centers in Malaysia offer the space for informality that allow stateless and undocumented people to seek out opportunities, while also finding ways to assimilate or even 'disappear' into the fabric of society. The book focuses on the notion of 'contaminations', rather than migration or migrants, to underscore one of the most important findings of the ethnographic study - that migrant life in Malaysia is critically integral, embedded and interwoven into the everyday life in the city - shaping and affecting all aspects of daily life from production and supply chains, food service networks, cultural and religious practices, waste and recycling work, to more intimate and private contexts such as romantic relationships, family life and sex-work. Hybridity, inter-mixing and bastardization are part and parcel of everyday urbanism in KL and Penang - these 'contaminating elements' challenge and disrupt categories of the 'national' and categories such as insider/outsider, national purity, and politically constructed divisions between ethnic and racial groups. The book thus relies upon detailed ethnographic narratives curated over a decade of study, offering students interested in fieldwork research insights into the types of engagements and commitments necessary for helping build the complex, uneasy and destabilizing knowledge that characterizes critical ethnography.