Which indeed? For nine chapters, English psychologist Eysenck and his collaborator judiciously and convincingly demolish the case for popular astrology--only to trumpet, in chapter ten, the case of Michel and Francoise Gauquelin for planetary effects on personality. According to the French couple, the eminent (and only the eminent) in certain fields--sports, medicine, music--show a tendency to birth times following the rise or the ""culmination"" of a particular planet: Mars for sports, Saturn for science, etc. They also find a correlation, in this respect, between the eminent and one or both parents, suggesting a hereditary factor. ""Perhaps it is this [genetic] predisposition,"" conclude the authors, ""that makes a child 'choose' to be born when a particular planet has just risen or culminated."" Actually, what correlates is not so much the chosen profession as associated strong personality traits, which presumably distinguish the eminent from the ordinary. Does this sound like traditional astrology? The authors think there is a link, though the Gauquelins eschew it. (Their sectors of the sky, in fact, are out of phase with the traditional ""houses"" of astrology.) As to the Gauquelins' findings, they pose multiple problems. Town records must be precisely accurate as to birth hour and verify that neither medication nor instrumentation was used (the birth must be wholly natural). Hour of birth must be related to onset of labor in postulating a signal of the planetary force. The element of self-fulfilling prophecy must be eliminated--e.g., the popular association between Mars and aggression (a contaminant in many studies of astrological ""accuracy""). Altogether, the astronomer G. O. Abell's quoted suspicion--that ""the Gauquelins' results will turn out to be spurious""--seems well-founded. Eysenck and Nias, on the contrary, defend the Gauquelins' methods and praise their scientific openness. They also see a future, not for astrology, but for ""cosmobiology""--a field incorporating the Gauquelins' work with that of Frank Brown (on animal sensitivities) and others. For the rest, the book supplies useful annotations of experiments that disprove or discredit popular astrology--from the daily columns to the Jupiter Effect.