Fifty-four adults with primary insomnia were randomly assigned to a self-help treatment (cognitive-behavioral bibliotherapy [BT]), BT with weekly phone consultations, or a waiting-list control (WL) group. Treated participants were mailed 6 treatment booklets at the rate of 1 booklet per week; 1/2 of them also received minimal professional guidance through a 15-min weekly phone consultation. The WL group members continued to monitor their sleep during this period. Participants in both treatment conditions improved significantly on the main outcome variables (total wake time and sleep efficiency) at posttreatment, whereas WL participants remained unchanged. The addition of weekly phone calls slightly enhanced improvements at posttreatment. However, both treatment conditions were comparable at follow-up. These results suggest that BT, with or without minimal professional guidance, is an effective approach for treating primary insomnia.