This paper provides an introduction to diary studies in the field of work and organizational psychology, highlighting their advantages and methodological considerations. Diaries are a valuable tool for capturing short-term fluctuations in work-related experiences and behaviors, which are often missed by traditional cross-sectional or survey methods. The authors discuss two recent diary studies: one examining the relationship between recovery experiences and mood the next morning, and another exploring the link between work characteristics and daily performance. They emphasize the importance of designing diaries to minimize respondent burden, ensuring compliance, and addressing issues such as missing data and sample size. The paper also covers various data collection devices, including paper-and-pencil diaries, handheld computers, and web-based surveys, and provides recommendations for sample recruitment and analysis. Finally, it suggests future research directions, such as applying diary studies to training and performance management, and examining mood trajectories over time.This paper provides an introduction to diary studies in the field of work and organizational psychology, highlighting their advantages and methodological considerations. Diaries are a valuable tool for capturing short-term fluctuations in work-related experiences and behaviors, which are often missed by traditional cross-sectional or survey methods. The authors discuss two recent diary studies: one examining the relationship between recovery experiences and mood the next morning, and another exploring the link between work characteristics and daily performance. They emphasize the importance of designing diaries to minimize respondent burden, ensuring compliance, and addressing issues such as missing data and sample size. The paper also covers various data collection devices, including paper-and-pencil diaries, handheld computers, and web-based surveys, and provides recommendations for sample recruitment and analysis. Finally, it suggests future research directions, such as applying diary studies to training and performance management, and examining mood trajectories over time.