The different stages of personality development in Maslow's self-actualization theory are most commonly known as his "hierarchy of needs." Essentially, these stages were really needs that had to be fulfilled, at least partially, before a person moved on to satisfy higher needs. It should be noted that they do not progress in a linear fashion like the stages in some developmental theories, however. Maslow's stages are as follows:
- Those needs that are the minimum for human survival, like food and water, shelter, and so on.
- The need for safety and security.
- The need for intimacy, love, and friendship.
- The need for a high self-esteem, and to be esteemed highly by others.
- The need for self-actualization, which was the term that Maslow used to describe a state of fulfilling one's potential.
Self-actualization was the highest of the stages, and Maslow, like others, posited that mental illnesses and disorders might result from not fulfilling needs at various points in one's life.