Diary studies are a valuable method in work and organizational psychology for examining short-term processes and everyday experiences of working individuals. This review article provides an introduction to diary studies, discusses methodological issues, and offers practical recommendations. Diary studies allow researchers to collect data at the daily level, capturing fluctuations in mood, performance, and other variables. They differ from traditional cross-sectional designs in that they provide data in natural settings, reducing retrospective bias and enabling the analysis of within-person changes over time. Diary studies can be of different types, including experience-sampling, event-sampling, and daily diaries, each with its own data collection methods. The article presents two examples of diary studies: one examining the relationship between recovery experiences and affect the next morning, and another exploring the relationship between work characteristics and daily performance. These studies highlight the importance of considering factors such as sample size, compliance, and data collection methods. Diary studies offer advantages over traditional surveys, including the ability to capture real-time data and reduce bias. However, they also present challenges, such as participant compliance and data collection device limitations. Researchers should consider the design of the diary questionnaire, the use of validated scales, and the appropriate analysis methods when conducting diary studies. Multilevel analyses are often necessary to account for the nested structure of data, with Level 1 representing daily observations and Level 2 representing stable characteristics. Centering methods, such as person-mean centering, are important for interpreting within-person effects. Control variables and the inclusion of weekend data should also be carefully considered to ensure the validity of results. Future research could explore the application of diary studies in areas such as training and performance management, as well as in the study of mood and stress trajectories. Diary studies provide a unique opportunity to examine dynamic processes in the work context, offering insights into how individuals' experiences and behaviors change over time.Diary studies are a valuable method in work and organizational psychology for examining short-term processes and everyday experiences of working individuals. This review article provides an introduction to diary studies, discusses methodological issues, and offers practical recommendations. Diary studies allow researchers to collect data at the daily level, capturing fluctuations in mood, performance, and other variables. They differ from traditional cross-sectional designs in that they provide data in natural settings, reducing retrospective bias and enabling the analysis of within-person changes over time. Diary studies can be of different types, including experience-sampling, event-sampling, and daily diaries, each with its own data collection methods. The article presents two examples of diary studies: one examining the relationship between recovery experiences and affect the next morning, and another exploring the relationship between work characteristics and daily performance. These studies highlight the importance of considering factors such as sample size, compliance, and data collection methods. Diary studies offer advantages over traditional surveys, including the ability to capture real-time data and reduce bias. However, they also present challenges, such as participant compliance and data collection device limitations. Researchers should consider the design of the diary questionnaire, the use of validated scales, and the appropriate analysis methods when conducting diary studies. Multilevel analyses are often necessary to account for the nested structure of data, with Level 1 representing daily observations and Level 2 representing stable characteristics. Centering methods, such as person-mean centering, are important for interpreting within-person effects. Control variables and the inclusion of weekend data should also be carefully considered to ensure the validity of results. Future research could explore the application of diary studies in areas such as training and performance management, as well as in the study of mood and stress trajectories. Diary studies provide a unique opportunity to examine dynamic processes in the work context, offering insights into how individuals' experiences and behaviors change over time.