Sampling is a critical component of qualitative research, yet it is often overlooked in methodological literature. This article presents a four-point approach to sampling in interview-based qualitative research, integrating theory and practice. The four points are: (1) defining a sample universe, (2) deciding on a sample size, (3) selecting a sampling strategy, and (4) sourcing cases. Each point is discussed in detail, with examples and considerations for both theoretical and practical aspects. Defining a sample universe involves setting inclusion and exclusion criteria to determine who can participate. This process helps define the study's scope and ensures that the sample is relevant to the research question. The level of homogeneity or heterogeneity in the sample universe depends on the criteria used. Homogeneous samples are useful for studies with specific theoretical foundations, while heterogeneous samples can provide broader generalizability. Deciding on a sample size involves considering both theoretical and practical factors. Theoretical considerations may dictate the need for a homogeneous sample, while practical considerations may influence the feasibility of a larger sample. The article discusses how sample size can be adjusted during the research process based on findings and resource availability. Selecting a sampling strategy involves choosing between random, convenience, or purposive sampling methods. Purposive sampling is often used in qualitative research to ensure that the sample includes individuals with specific characteristics relevant to the study. Strategies such as stratified, cell, and quota sampling are discussed, along with theoretical sampling, which is used to refine the sample based on emerging data. Sourcing cases involves recruiting participants from the sample universe. This process requires ethical considerations, including informed consent and minimizing bias. Advertising, referral processes, and incentives are discussed as methods for recruiting participants. Incentives can increase participation but may also introduce bias, so they should be used judiciously. The article emphasizes the importance of sampling in ensuring the validity and reliability of qualitative research. A well-defined sampling strategy enhances the study's sensitivity to context, rigor, transparency, coherence, and impact. The four-point approach provides a framework for researchers to systematically address sampling issues, leading to more valid and credible findings. The strategies and concepts discussed are not exhaustive but offer a foundation for researchers to innovate and adapt sampling methods to their specific research needs.Sampling is a critical component of qualitative research, yet it is often overlooked in methodological literature. This article presents a four-point approach to sampling in interview-based qualitative research, integrating theory and practice. The four points are: (1) defining a sample universe, (2) deciding on a sample size, (3) selecting a sampling strategy, and (4) sourcing cases. Each point is discussed in detail, with examples and considerations for both theoretical and practical aspects. Defining a sample universe involves setting inclusion and exclusion criteria to determine who can participate. This process helps define the study's scope and ensures that the sample is relevant to the research question. The level of homogeneity or heterogeneity in the sample universe depends on the criteria used. Homogeneous samples are useful for studies with specific theoretical foundations, while heterogeneous samples can provide broader generalizability. Deciding on a sample size involves considering both theoretical and practical factors. Theoretical considerations may dictate the need for a homogeneous sample, while practical considerations may influence the feasibility of a larger sample. The article discusses how sample size can be adjusted during the research process based on findings and resource availability. Selecting a sampling strategy involves choosing between random, convenience, or purposive sampling methods. Purposive sampling is often used in qualitative research to ensure that the sample includes individuals with specific characteristics relevant to the study. Strategies such as stratified, cell, and quota sampling are discussed, along with theoretical sampling, which is used to refine the sample based on emerging data. Sourcing cases involves recruiting participants from the sample universe. This process requires ethical considerations, including informed consent and minimizing bias. Advertising, referral processes, and incentives are discussed as methods for recruiting participants. Incentives can increase participation but may also introduce bias, so they should be used judiciously. The article emphasizes the importance of sampling in ensuring the validity and reliability of qualitative research. A well-defined sampling strategy enhances the study's sensitivity to context, rigor, transparency, coherence, and impact. The four-point approach provides a framework for researchers to systematically address sampling issues, leading to more valid and credible findings. The strategies and concepts discussed are not exhaustive but offer a foundation for researchers to innovate and adapt sampling methods to their specific research needs.