Systems development encompasses systems analysis and systems design. Systems analysis is related with studying a system in depth to identify the limitations of the system and to discover features that can be added in order to improve the system. Such essential features are called requirements of the proposed system. Identification of good requirements and specifying them in an effective manner are essential activities during the systems development. Envisioning high-quality requirements leads to good-quality system. This chapter defines requirements determination process. The requirements anticipation, requirements investigation, and requirements specification are discussed thoroughly. The chapter also discusses requirements investigation in detail by providing discussion on fact-finding techniques such as interview, questionnaire, record review, observation, and prototyping. Decision tree, various types of decision tables, and structured English with its different forms are also discussed in this chapter. Many examples of the decision tree, table, and structured English are provided in this chapter. This chapter also discusses conversion of decision table into tree/structured English and vice versa with the help of real-life situations. The chapter provides various practice questions with answers at the end as well as objective questions with answers.