We report findings from two large-scale randomized experiments, carried out on the British Household Panel Survey, with survey features designed to reduce sample attrition. The first experiment compares strategies for obtaining updated contact information from sample members. We find that the propensity to locate a sample member at wave t successfully is maximized by a between-wave mailing of a change-of-address card, rather than an address confirmation card or no card. The second experiment compares standardized and tailored respondent reports for young people and busy people. We find that tailored reports have a modest positive effect on rates of co-operation for both groups, though the effect for busy people depends on providing the option of a shorter telephone interview instead of the full face-to-face interview.