More needs to be known about the phoning logistics of interviewing subjects for longitudinal follow-up studies in the domestic violence field. Using phoning logs from a 4-year follow-up of batterer intervention, the authors calculated the number, results, and costs of phone calls from a sub sample of 100 men and 138 women. The number of calls is high (5.5 per man and 7.1 per woman), locators play a substantial role (for 25% of the men and women), and mailed questionnaires are a useful supplement (increasing response rate 5% for men and 11% for women). On average, about half of the subjects were interviewed at each interval. The main obstacle is not refusals but no response and not being able to locate a subject. Strategies to address "no response" are considered.