Service systems for children and families have been shaped by standard approaches to knowledge-building, which reflect a reductionist approach and assume linearity and/or that individuals and experiences are normally distributed. Yet, these approaches may be inadequate for clients most at-risk, especially those who would be analytic ‘outliers’. A complexity lens focuses on the whole system and seeks to identify patterns, including the dynamic interactions between components of the system. Social work scholars have begun to apply complexity theory to social work research efforts, demonstrating the conceptual potential of incorporating this theoretical approach into social work theories and models such as the person-in-environment framework and the ecosystems perspective. Yet, frameworks informed by complexity theory may require ontological and epistemological shifts in thinking and new methodological approaches in order to fully embody a complexity approach. Complexity theory offers the opportunity to consider social work clients who are most at-risk, as it is better suited for power law distributions. We can, therefore, reconceptualize the most ‘at-risk’ clients as being in a state of transition, which is also the space of most creativity and possibility.