This paper critically reviews the ethological attachment theory as proposed by Bowlby and Ainsworth in order to examine if attachment theory is a great idea in personality. The most important aspects of attachment theory are presented and two critical questions are posed. The first question is, Can attachment theory be supported by empirical evidence? To answer this question, a variety of studies will be reviewed, each of which examines a specific aspect of attachment theory. The second question is whether the phenomena explained by creators and proponents of ethological attachment theory could have been explained differently, using other psychological mechanisms. These are two criteria that must be met if attachment theory is to be considered a great idea.