This article provides a comprehensive guide to sampling in qualitative interview-based research, emphasizing its central role in the research process. It outlines a four-point approach to sampling: defining a sample universe, deciding on a sample size, selecting a sampling strategy, and sourcing samples. The article discusses the theoretical and practical considerations for each step, including the importance of specifying inclusion and exclusion criteria, the impact of sample size on generalizability, various sampling strategies such as random, convenience, purposive, stratified, cell, quota, and theoretical sampling, and ethical considerations in sample sourcing. It highlights the trade-offs between homogeneity and heterogeneity in the sample universe, the flexibility in sample size adjustments, and the challenges of self-selection bias. The article also explores methods for recruiting participants, such as advertising, snowball sampling, and the use of incentives. Finally, it emphasizes the importance of addressing these sampling issues to enhance the validity, transparency, and impact of qualitative research.This article provides a comprehensive guide to sampling in qualitative interview-based research, emphasizing its central role in the research process. It outlines a four-point approach to sampling: defining a sample universe, deciding on a sample size, selecting a sampling strategy, and sourcing samples. The article discusses the theoretical and practical considerations for each step, including the importance of specifying inclusion and exclusion criteria, the impact of sample size on generalizability, various sampling strategies such as random, convenience, purposive, stratified, cell, quota, and theoretical sampling, and ethical considerations in sample sourcing. It highlights the trade-offs between homogeneity and heterogeneity in the sample universe, the flexibility in sample size adjustments, and the challenges of self-selection bias. The article also explores methods for recruiting participants, such as advertising, snowball sampling, and the use of incentives. Finally, it emphasizes the importance of addressing these sampling issues to enhance the validity, transparency, and impact of qualitative research.