The first 90 days in a new role is a critical period where expectations are highest and impression-forming happens fastest. Michael Watkins' framework emphasizes: (1) Secure early wins (visible deliverables that prove you deliver), (2) Deepen stakeholder relationships (1:1s with peers, leadership, cross-functional partners), (3) Learn the organization (history, culture, politics, priorities), (4) Clarify your mission (what's success?), (5) Adapt your leadership style to the organization. Practitioners who master this process are promoted faster because they establish credibility, understand culture, and contribute immediately.