<p>Applied behavior analysis (ABA) organizations face increasing pressure from clients, caregivers, clinicians, and payors to demonstrate meaningful and measurable outcomes of the care they provide. Individualistic approaches often rely heavily on goal mastery, which is sensitive to short-term change and aligned with individualized treatment, but fails to capture broader domains such as functional relevance, quality of life, or allow for comparison across clients and providers. Conversely, standardized assessments provide scalability and comparability but can be costly, burdensome, or insufficiently tailored to client priorities. This manuscript offers a first-principles framework for designing a balanced outcomes measurement portfolio in ABA that integrates client-centered design, interest-holder perspectives, and multiple outcome dimensions. We describe a structured, five-step decision-making process (defining purpose, identifying domains, scanning candidate measures, aligning with organizational constraints, and validating with interest-holders) and an implementation roadmap that emphasizes readiness, workflow integration, piloting, and continuous improvement. Drawing on lessons learned from a large multi-site ABA organization, we illustrate how individualized and standardized measures can be combined to maximize clinical utility, accountability, and social validity while remaining feasible to implement. Outcome measurement in ABA should be an iterative, living system that evolves with client needs, organizational capacity, and scientific evidence, and that is anchored in socially significant behavior change. This guide provides one practical method whereby ABA providers can design and sustain the implementation of outcome portfolios that are rigorous, client-centered, and responsive to the complex demands of modern healthcare service delivery.</p>