Following the definition of the constructs trust, trustworthiness, and justice, a detailed description of social-psychological theories of justice is provided. The various dimensions of justice, such as distributive and procedural justice, are examined, as well as the question of whether people are inherently fair and how the motivation for justice develops in children. Furthermore, the theory of the just world belief is discussed, which posits that people have a need to live in a just world. The just world belief enables them to trust that good things will happen to them if they behave well. The subsequent section of the chapter is devoted to the reciprocal interplay between justice and trust. Finally, the relevance of trust and justice in the context of cooperation is addressed.