Sexual maturity occupies a structurally pivotal position in the depth-psychological corpus, functioning simultaneously as a developmental milestone, a normative ideal, and an analytic problem. Freud’s foundational treatment in the Three Essays on the Theory of Sexuality (1905) establishes the template: sexual maturity is not a sudden biological event but the culmination of a diphasic developmental process, reaching its decisive resolution at puberty when component instincts must achieve genital synthesis. For Freud, the entire edifice of neurosis rests upon failures, fixations, and regressions along this developmental arc. Jung complicates the picture by insisting that psychological puberty frequently outlasts biological puberty, and that genuine maturity of judgment in men may lag years behind that of women — a claim grounded not in biology but in the psyche’s differential readiness. Masters (2012) radicalises the concept by arguing that sexual maturity is irreducibly multi-dimensional: intellectual, emotional, moral, psychological, and spiritual development must converge before genuine sexual maturity is achievable. Panksepp’s affective neuroscience grounds the question neuroendocrinologically, tracing how puberty reorganises hypothalamic circuits whose organisational effects were laid down prenatally. Across these traditions, a persistent tension runs between biological and psychological definitions of maturity, and between developmental telos and the recognition that most persons remain, in significant respects, sexually immature.