Defense styles refer to the characteristic employment of automatic psychological processes to maintain and enhance self-esteem. On the basis of clinical literature pertaining to defense styles, it was hypothesized that the maturity of an individual\u27s defenses would be associated with fluctuations in one\u27s state self-esteem over time (i.e., self-esteem instability). To examine this hypothesis, the present study included daily diary measures that tracked the state self-esteem of 123 participants each day for 14 consecutive days. The results of the present study found that higher levels of immature defenses were associated with greater self-esteem instability. For both the intermediate and mature defense styles, their associations with self-esteem instability were moderated by self-esteem level such that higher levels of these defenses were associated with less self-esteem instability among those with low self-esteem. (c) 2007 Elsevier Inc. All rights reserved
