Research combining unobtrusive observation and interview methods assessed the effectiveness of a pilot food-scrap recycling program at Sea-Tac Airport. Observers on a balcony recorded 1,398 travelers’ recycling behavior. They randomly selected from those travelers and used radios to alert a survey worker stationed some distance from the recycling station below to approach the selected traveler and conduct a short interview (using a tablet computer). Presentation biases were minimized because travelers were unaware that their recycling behavior was recorded, but interviews and observations were linked. Results showed opportunities to increase program effectiveness – 75 percent of all travelers did not sort waste into more than one bin; at least 15 percent dumped all waste in an incorrect bin; 11 percent sorted at least one item into an incorrect bin. Further analyses suggested that the pilot program could increase its effectiveness by making it easier for travelers to correctly divert recyclable materials.#MixedMethodsEvaluation #2012Conference #EnvironmentalProgramEvaluation