Much of the literature on random-digit-dial (RDD) response rates focuses on the benefits and drawbacks of various screening and sampling procedures. The common assumption is that enumeration is more invasive, leading to lower response rates, but there are concerns about population coverage and self-selection with other methods. When the target population is found in a subset of households, a screen-out question may be used to eliminate ineligible households prior to employing sampling methods. Using approximately 10,000 telephone numbers from the National Household Education Survey (NHES) sampling frame, this experiment examined the impact on screening response rates of: full enumeration of all households (no screen-out) versus a screen-out question, and mailing an advance letter. An RDD sample was divided into four quarter samples: (1) screen-out and letter; (2) screen-out and no letter; (3) no screen-out and letter; and (4) no screen-out and no letter. Response rates were significantly higher in the screen-out condition. The advance mailing increased cooperation in the no screen-out condition, but not in the screen-out condition. The no screen-out condition consumed substantially more resources than a screen-out sample of the same size, but also provided more data for each completed case. Implications of this experiment for the design of future surveys are discussed. Two appendixes present the NHES field test letter and the advance letter. (Contains 7 tables, 1 exhibit, and 24 references.) (Author/SLD)