Staff augmentation gets a bad reputation when used as a procurement shortcut rather than a workforce strategy. Done well, it compresses time-to-impact and absorbs demand variance without permanently inflating the org chart. Done badly, it produces a quiet tax on velocity nobody notices until the contractors leave. This 22-page playbook is for engineering leaders who know they need external capacity and want a defensible operating model. We open with a framework for the four legitimate use cases -- skill injection, demand smoothing, geographic extension, capability seeding -- and three anti-patterns that destroy programs. The middle covers contractual primitives (IP assignment, screening, data-handling addenda, right-to-replace), interview rubrics that predict hybrid-team effectiveness, and onboarding rituals that compress time-to-first-PR from 14 days to five. Closes with the metrics that distinguish a healthy program from a deteriorating one.