All adolescents in general, including ethnic and racial minorities, report high levels of cell phone use, making mobile technology a useful tool for assessment and intervention. Known health and education disparities based on minority status motivated us to conduct an in-depth investigation regarding feasibility of and adherence to the ecological momentary assessment (EMA) research protocol, studying daily life of urban minority youth. In addition, this paper presents a methodological approach to conceptualizing and reporting adherence in EMA studies. The sample was comprised of 126 youth (41.3% boys; 40.5% 7th and 59.5% 8th graders; 75.4% African American, and 20.6% Hispanic) who carried a mobile phone for 10 days, including 2 weekends and reported on activities, moods, and attitudes. Mean level of adherence was 81% for momentary and 93.8% for daily assessments; it decreased over time and was higher during the week compared to weekends. Adherence was lower on days when participants reported high levels of negative affect and on days when they were engaged in physical activities. Our findings underscore the importance of differentiating between human and technology-related factors when computing adherence rates and portray adherence as a complex and dynamic construct that can vary across individuals. Specific study recommendations and methodological discussion provide guidelines for designing future studies.