Abraham Maslow (1908 - 1970) was an American psychologist most famous for his 'hierarchy of needs' model. This theory states that the needs of a human being come in a strict order with the most basic (food, water) taking precedence over less necessary needs such as friendship. His theory was that the most basic needs needed to be satisfied before the next 'layer' of needs became a consideration. A full list from most to least important is beneath.

Critics of the theory point to the fact that it was never scientifically tested, and is biased towards Western cultural values. Nevertheless, it remains popular in the leadership development and coaching disciplines.