Over the ten years following the August Session of the All-Union Lenin Academy of Agricultural Sciences in 1948, which determined the future direction of the development of materialist biology, no conference on problems of genetics was convened. During this period, scientists of the Michurin school accumulated a large body of new factual material, enriching materialist science and creating an urgent need for its systematic summarization. “Classical genetics” also underwent major changes. The experimental data it accumulated made the untenability of the fundamental theoretical positions of formal genetics increasingly apparent, even to the representatives of that school themselves. The advocates of “classical genetics” abandoned these views and replaced them with new ones, yet they continued to attempt to fit facts that contradicted chromosome theory and gene theory into the framework of those same theories. Naturally, this not only failed to free “classical genetics” from its metaphysical system, but in fact preserved that system in its entirety, despite attempts to provide a physicochemical foundation for the doctrine of a mysterious hereditary substance that exists apart from life while determining all of its characteristics. It must be emphasized that some of our biologists have promoted these new systems as the greatest achievements of “classical genetics.” In view of these circumstances, the Organizing Committee of the Anniversary Conference of the Institute of Genetics of the Academy of Sciences of the USSR, established to commemorate the 40th anniversary of the Great October Socialist Revolution, considered it necessary to convene a broad conference on problems of genetics. The conference invited participants from the biological institutes and branches of the Academy of Sciences of the USSR, the academies of sciences of the Union republics, the All-Union Lenin Academy of Agricultural Sciences, the Academy of Medical Sciences of the USSR, universities and other institutions of higher education, research institutions of various ministries and administrative bodies, as well as individual scientists from across the country. In addition to the plenary sessions, four sections were organized: Directed Variation in Plants, Heredity and Viability, Animal Genetics, and Genetics of Microorganisms and Viruses. At the plenary and sectional meetings, approximately 200 reports on various problems of genetics were presented; about 100 participants took part in the discussions of these reports. More than 1,000 people participated in the work of the conference. The conference proceedings, published in two volumes under the general title Heredity and Variability in Plants, Animals, and Microorganisms, did not fully encompass all the materials generated by the conference. Owing to the abundance of material, the Editorial Committee was compelled to forgo publication of the discussion speeches on individual reports and limited itself to listing the names of those who participated in the discussions; reports presented at the sectional meetings were published in abbreviated form. The Editorial Board hopes that the publication of the conference materials will contribute positively to the further development of materialist, Michurinian genetics.