Roads are among the most widespread human infrastructures worldwide, and their rapid expansion in biodiversity-rich regions raises urgent concerns for conservation. While research in Road Ecology has traditionally focused on direct mortality, habitat loss, and fragmentation, behavioral responses of wildlife to roads and traffic are increasingly recognized as critical drivers of ecological outcomes. These responses encompass a continuum from attraction to avoidance, each carrying distinct implications for survival, reproduction, and movement. Attraction may arise when roads provide nesting substrates, thermoregulatory sites, or novel foraging opportunities, while avoidance emerges from physical barriers, unsuitable surfaces, or sensory disturbances such as noise, light, and chemical pollution. Together, these behaviors shape the barrier effect, defined as the aggregate of individuals that fail to complete a crossing due to roadkill or avoidance. Four broad behavioral categories (nonresponders, pausers, speeders, and avoiders) illustrate how species experience the barrier effect through different mechanisms, with profound consequences for connectivity and population dynamics. Looking forward, advancing Road Ecology requires broadening the taxonomic and geographic scope of behavioral studies, particularly in underrepresented tropical regions and among less-studied taxa. Behavioral metrics should be systematically integrated into impact assessments and mitigation planning, as they provide early-warning indicators of functional connectivity loss. Moreover, behavioral responses to roads interact synergistically with those elicited by other infrastructures such as railways and power lines, reinforcing the need for network-scale approaches. Emerging technologies, from GPS telemetry to drones and machine-learning analytics, offer unprecedented opportunities to quantify and model these processes. Integrating behavioral ecology into research, policy, and practice is therefore essential to ensure effective conservation in an increasingly roaded world.