We present an architecture-centric approach for achieving traceability between stakeholders' quality concerns, architecturally significant requirements, design rationales, and source code. In Decision-Centric Traceability (DCT), all trace links are focused around architectural decisions that include factors as varied as platforms, languages, frameworks, patterns, and lower-level architectural tactics. We show how DCT supports critical software engineering activities such as safety-case construction, impact analysis, stakeholder satisfaction analysis, requirements validation, and architectural preservation. Our approach is illustrated and validated with examples drawn from the architectural decisions and subsequent design of the TraceLab project funded by the US National Science Foundation under a Major Research Infrastructure grant.