This chapter argues that research on subjective well-being (SWB) has evolved from reductionist, single-factor models toward more integrative, multi-level frameworks accounting for biological, psychological, social, situational, and cultural determinants. Its primary aim is to synthesize evidence across these dimensions, delineating a layered conceptual architecture that incorporates endogenous personal attributes, interpersonal socio-demographic factors, and situational environmental influences. Section 4.1 traces the theoretical shift from static classifications to dynamic interactional models, exemplified by the biopsychosocial-ecological framework. Section 4.2 examines endogenous determinants, including genetic and epigenetic mechanisms and psychological traits. Section 4.3 analyzes demographic and socioeconomic variables, while Sect. 4.4 explores interpersonal and situational factors such as social networks and built environment characteristics. Section 4.5 discusses macro-level influences from cultural, institutional, and urban planning contexts. The chapter concludes with Sect. 4.6, which proposes integrative frameworks and highlights implications for policy and interdisciplinary research. By contextualizing SWB within a multi-dimensional ecosystem, this chapter provides a foundational lens for understanding well-being determinants and sets the stage for subsequent empirical analysis of built environment effects in high-density urban settings.