Hellenistic astrology is a tradition of astrology that developed in the eastern Mediterranean world from roughly the 2nd century BCE through late antiquity, synthesizing earlier Babylonian celestial omen practices and horoscopic techniques with Egyptian and Greek philosophical and mathematical frameworks. It is distinguished from earlier Babylonian astrology by its use of the natal horoscope - a chart cast for the precise moment of an individual's birth - and from later astrological traditions by its specific technical apparatus, including the twelve-sign zodiac, the twelve houses (places), planetary rulerships, aspects, and a body of predictive techniques such as profections and zodiacal releasing. The most systematic surviving exposition of the tradition's theoretical foundations is the Tetrabiblos of Claudius Ptolemy (2nd century CE), though Ptolemy's framework was not universally accepted by other practitioners of the era, and significant portions of the technical tradition - preserved in figures such as Vettius Valens and Dorotheus of Sidon - diverge from or omit Ptolemaic theory. The term “astrology” in this article refers to the practice and its associated body of techniques and beliefs; whether the underlying claims of astrology are valid is a contested empirical question addressed in astrology-validity-debate and related pages.

Hellenistic astrology is studied today primarily as a subject of historical, philological, and history-of-science research rather than as an active scientific framework. Scholars in classics, the history of science, and Near Eastern studies work to reconstruct its techniques from fragmentary and often poorly transmitted Greek and Demotic Egyptian papyri, later Byzantine and Arabic compilations, and translations into Persian and Sanskrit that preserved material lost in the original Greek. Since the late 20th century a separate community of practicing astrologers, working largely outside academia, has undertaken translation and reconstruction projects aimed at reviving Hellenistic techniques for contemporary astrological practice; this revival movement is distinct from the academic study of the tradition's history, though the two communities draw on overlapping primary sources. Consistent with the empirical consensus noted below, astrology generally - including its Hellenistic form - is not regarded by researchers in astronomy, physics, and psychology as a valid predictive or explanatory framework for human affairs; this assessment concerns the predictive validity of astrology as a practice, not the value of Hellenistic astrology as a historical or philological subject of study, which is treated as a legitimate area of scholarship independent of that assessment. For the longer historical development of the tradition, see hellenistic-astrology-history.

There is broad consensus among historians of science regarding the chronological development and technical content of Hellenistic astrology - its Babylonian and Egyptian antecedents, its diffusion through the Greco-Roman world, and its technical vocabulary - reconstructed through philological and papyrological evidence. See hellenistic-astrology-historical-development-consensus. Separately, there is broad consensus among researchers in astronomy, physics, and psychology, arrived at independently across institutions, that astrology's claims of predictive validity lack empirical support under controlled testing; this consensus addresses astrology as a predictive practice generally and is not specific to the Hellenistic period. See astrology-predictive-validity-consensus.

• Ptolemaic-rationalist viewpoint: Holds that Ptolemy's Tetrabiblos represents the most philosophically coherent attempt to ground astrology in natural causation (planetary influence transmitted through physical means analogous to heat and light), and that later astrologers' more elaborate techniques lack this grounding. See hellenistic-astrology-ptolemaic-rationalist-viewpoint.
• Traditionalist-technical viewpoint: Held by practitioners and scholars of the contemporary Hellenistic revival, this viewpoint holds that the pre-Ptolemaic technical tradition (Dorotheus, Valens, Antiochus of Athens) is more representative of mainstream ancient practice than Ptolemy, and that modern astrology lost effectiveness by discarding techniques such as whole-sign houses and ancient planetary triplicity rulers. See hellenistic-astrology-traditionalist-technical-viewpoint.
• Historicist-contextualist viewpoint: Common among classicists and historians of science, this viewpoint treats Hellenistic astrology as a coherent product of its intellectual environment - continuous with ancient astronomy, medicine, and philosophy - worth reconstructing on its own terms without assessing its predictive claims. See hellenistic-astrology-historicist-contextualist-viewpoint.
• Skeptical-empiricist viewpoint: Holds that astrology, including its Hellenistic form, fails as a predictive system under empirical testing and that any apparent validity is attributable to confirmation bias, the Barnum effect, and selective memory. See astrology-skeptical-empiricist-viewpoint.
• Esoteric-symbolic viewpoint: Held by some practitioners, this viewpoint treats astrology's value as residing in its symbolic and psychological utility - a framework for self-reflection and meaning-making - independent of literal predictive claims. See astrology-esoteric-symbolic-viewpoint.

• Whether Ptolemy's astronomical and astrological work, given his documented use of intentionally fabricated or adjusted observational data in some contexts, should be read as a sincere scientific synthesis or a rhetorically convenient systematization built atop existing folk practice. See claudius-ptolemy-scientific-integrity-controversy.
• The dispute over whether “whole sign” or “quadrant” house systems represent the original or dominant Hellenistic practice, with implications for the legitimacy claims of modern revival movements. See hellenistic-astrology-house-system-controversy.

• hellenistic-astrology-history
• astrology-validity-debate
• hellenistic-astrology-ptolemaic-rationalist-viewpoint
• hellenistic-astrology-traditionalist-technical-viewpoint
• astrology-predictive-validity-consensus
• hellenistic-astrology-historical-development-consensus
• claudius-ptolemy-scientific-integrity-controversy
• hellenistic-astrology-house-system-controversy
• babylonian-astrology
• Claudius Ptolemy - Astrology Viewpoint

• Ptolemy, Claudius. Tetrabiblos. Translated by F. E. Robbins. Loeb Classical Library. Cambridge, MA: Harvard University Press, 1940.
• Barton, Tamsyn. Ancient Astrology. London: Routledge, 1994.
• Beck, Roger. A Brief History of Ancient Astrology. Malden, MA: Blackwell Publishing, 2007.
• Jones, Alexander. “The Astronomical Tradition in Ptolemy's Tetrabiblos.” In Ptolemy in Perspective: Use and Criticism of His Work from Antiquity to the Nineteenth Century, edited by Alexander Jones, 35-49. Dordrecht: Springer, 2010.
• Pingree, David. “Astrology.” In Dictionary of the History of Ideas, vol. 1, edited by Philip P. Wiener, 118-126. New York: Charles Scribner's Sons, 1973.
• Heilen, Stephan. “Some Metrical Fragments from Nechepso and Petosiris.” In La poesía astrológica en la Antigüedad y la Edad Media, edited by Aurelio Pérez Jiménez, 23-93. Madrid: Consejo Superior de Investigaciones Científicas, 2010.
• Holden, James Herschel. A History of Horoscopic Astrology. 2nd ed. Tempe, AZ: American Federation of Astrologers, 2006.