This paper explores the impact of test-taking conditions on the quality of the Programme for the International Assessment of Adult Competencies (PIAAC) assessment. Interviewers record information about the room of assessment and interruptions that occurred during each interview. These observations, along with information on interviewer assignment size and a careful look at interviewer effects, provide insights into the quality of the assessment. This working paper first describes the variations in test-taking conditions among participating countries. Second, it examines interviewer assignment sizes and the frequency of interruptions, finding that both vary markedly among countries (contrary to the room of assessment). The paper then looks at the relationship between these variations and response rates and engagement measures. While neither the room of assessment nor the recorded interruptions impact quality differences among countries, interviewer assignment size and interviewer effects may have a mild impact on results.