Sex and gender are among the most heavily investigated interindividual factors in all areas of psychology. Although sex and gender have been studied for more than a hundred years, there has been an explosion of theories and research in this area in the past several years. Whether psychological differences between men and women truly exist, and where they originate, is still under debate. Although the majority of experts would deny that sex and gender differences in mind and behavior are either purely biological or purely social in origin, it seems that the proportions attributable to nature and nurture are still being negotiated. New research takes into account biological and social factors, as well as the interaction between them, and addresses ‘‘the small difference’’ within a psychobiosocial approach. This topical issue integrates research on sex and gender differences from various psychological disciplines and emphasizes a psychobiosocial approach as a promising new perspective in this field. In January 2005, Larry Summers, then president of Harvard University, gave a speech at the ‘‘Diversifying the Science and Engineering Workforce’’ conference held by the National Bureau of Economic Research in Cambridge, MA, that elicited a political and social earthquake. In his attempt to answer the question why women are underrepresented in top academic careers, he offered three potential explanations: (1) He argued that more young mothers than fathers are unwilling to spend 80 hr per week at work. (2) More boys than girls tend to be at the highest or lowest end of mathematical performance in high schools. Although boys and girls do not show significant differences in mean mathematical performance, a higher proportion of boys reveal extremely high mathematical aptitude, which might explain why women are underrepresented in the upper echelons of academic and professional life. (3) Finally, Summers admitted that discrimination at universities exists, including at Harvard University, but this may be less relevant because women are already underrepresented below the top level of academic leadership. His second point especially not only led to many attendees indignantly leaving the hall, but also revived a worldwide debate. Is there empirical evidence for ‘‘innate’’ sex differences in cognitive abilities? Is there new empirical support for a biological basis for cognitive differences between men and women? What are the social factors that elicit or promote sex and gender differences? Although a lot of research has been done on these issues, many questions remain unanswered and an appraisal of new perspectives and new findings thus appears necessary from time to time (see, e.g., Schober, Reimann, & Wagner, 2004). In light of this, the present topical issue ‘‘Sex and Gender Differences Revisited – New Perspectives and New Findings’’, on the one hand, contains contemporary studies of sex differences in specific cognitive variables, focusing on some relevant biological and social factors underlying the ‘‘small difference,’’ and, on the other hand, presents new findings on mechanisms behind gender differences from more applied research on education, work, and science. Finally, it includes two opinion papers with the explicit aim of discussing new perspectives and possible reconciliations between very different research approaches to sex and gender. Cognitive tests favoring men mainly include specific mathematical and spatial problems such as mental rotation, an ability that involves the ability to imagine and mentally manipulate 3D objects. Because mental rotation is particularly sex-sensitive so that men outperform women with effect sizes up to one standard deviation, sex differences in mental rotation are the focus of various psychological approaches. Neuburger, Jansen, Heil, and Quaiser-Pohl (2012) focus on gender stereotypes and their effects on mental rotation performance in primary school children. Gender stereotype effects on cognitive abilities in general, and mental rotation in particular, have been reported before (e.g., Hausmann, Schoofs, Rosenthal, & Jordan, 2009). It has remained