Objective: To conduct a dietary intervention using the Personal Nutrition Planner (PNP), an on-line nutrition intervention tool. Design: Randomized controlled trial with pretest, posttest, and 2-month follow-up self-report assessments. Setting: Web/on-line. Participants: Female university staff (n = 307; 59.1% Caucasian) recruited via e-mail. Retention rate was 85.0% (118 treatment; 143 comparison). Intervention: PNP on-line produces individualized nutrition feedback based on initial on-line assessment. Intervention lasted 5 weeks and included weekly e-mail reminders. Main Outcome Measures: Dietary intake frequencies, weight loss, opinions regarding intervention. Analysis: Repeated-measures analysis of variance to determine intervention effects on dietary intake and weight loss (P less than 0.05). Results: Relative to the comparison group who received no program, the treatment group increased dairy intake frequency across the 3 assessments (F[subscript 2,304] = 3.15; P less than 0.05). Among participants who wanted to lose weight, weight loss in the treatment group was significantly higher than that of the comparison group from pretest to posttest (F[subscript 1,92] = 4.50; P less than 0.05). On a scale of 1-5, mean ratings of the PNP program characteristics ranged from 3-4. Conclusions and Implications: PNP produced significant increases in dairy intake and decreases in weight. Further revisions will tailor PNP to better fit individuals' dietary goals and increase motivation.