This study examines the Islamic concept of Al-Wala’ wal Bara’ (Loyalty and Disavowal) in modern Salafism referred to here as WB. The research is divided into two parts. Part One introduces the phenomenon of modern Salafism and the concept of WB (Chapter One). It also demonstrates how the Quran, particularly its sixtieth chapter (Surah Al-Mumtahanah) and the concept of Millat Ibrahim (Religion of Abraham) play an important role in formulating the modern Salafi concept of WB (Chapter Two). Part Two discusses the realities and complexities of the concept. First, the concept in Wahhabism, whose adherents form the majority of modern Salafis, and whose tradition is believed to have influenced and shaped modern Salafism, is discussed (Chapter Three). The complexities of WB are described as the research recognizes the diversity or “spectrum” of the concept in modern Salafism, which ranges from what might be termed “very mild” to “very extreme” (Chapter Four). The research shows that one of the main reasons for this diversity is the different Salafi orientations or the backgrounds from which modern Salafis emerge. This is proven through analyzing the writings on WB by Salafis of purist, politico and Jihadi backgrounds – a specific categorization of modern Salafis used for the purpose of this research (Chapter Five). The analysis is conducted by mainly observing the role of WB within their intellectual systems. Through this analysis, it is concluded that a particular Salafi orientation has an effect on the style of writing and presentation of the concept by modern Salafis. This reflects the position of WB in modern Salafism as being fluid and multi-dimensional. The research then, aims to explore the centrality, breadth and complexity of the WB concept in modern Salafism, and proves that WB in modern Salafism is not static but flexible and dynamic. The significance of the research lies in the fact that understanding modern Salafi conceptions of WB is an urgent priority in the lives of Muslims today. This understanding is critical, as Muslims increasingly live as minority communities across the globe and WB has specific implications for whether (and how) Muslims can live with non-Muslims. The research concludes that the consequences of applying the modern Salafi concept of WB are serious – WB generally promotes a way of life that is insular and hostile towards non-Muslims and this, it might be argued, is at variance with more tolerant, inclusive nature of Islam.