Project scope management and change control form the backbone of successful project execution, yet they remain the most frequently mismanaged knowledge areas. While 52% of projects experience scope creep according to PMI research, the root cause isn't poor documentation—it's the failure to establish shared understanding between stakeholders and teams about what constitutes "in" versus "out" of scope. Effective scope management requires balancing three competing forces: stakeholder expectations (often optimistic), technical reality (usually constrained), and organizational capacity (inevitably limited). The most successful project managers treat scope as a living contract that evolves through formal change control, not as a static document that gets ignored when reality intervenes. This cheat sheet synthesizes PMBOK-aligned processes with Agile adaptations, providing actionable frameworks for defining boundaries, managing change requests, preventing creep, and maintaining alignment from initiation through closure.