The present study tested positive automatic thoughts, negative automatic thoughts, and States of Mind(SOM) ratio to moderate or mediate the relation between life stress and depression. College students completed self-report measures of life stress, the positive and negative automatic thoughts, and Beck Depression Inventory. Results suggested that positive automatic thoughts and negative automatic thoughts served as a mediator(but not a moderator) of the relation between life stress and depression. SOM ratio served as not only a mediator but also a moderator of the relation between life stress and depression. Some limitations and considerations for future research were discussed.