This chapter provides a comprehensive guide to the maintenance of C. elegans in the laboratory. It covers the acquisition of worm strains from the Caenorhabditis Genetics Center (CGC), methods of culture and transfer, decontamination of stocks, synchronizing and staging cultures, and procedures for freezing worms for long-term storage and for recovering them from the frozen state. The CGC provides C. elegans strains and information to researchers, and maintains an up-to-date bibliographic list of all articles, reviews, and books discussing C. elegans. The Worm Breeder's Gazette, a newsletter, is available for subscription. To acquire strains, researchers can submit a written request describing the strains, genes, or alleles desired and a brief statement of the intended use of the worms. The CGC provides strains for free to researchers at educational institutions or non-profit organizations, while commercial organizations must pay a fee. Strains are sent on NGM petri plates with the worms still feeding on E. coli OP50 or starved, depending on the strain's phenotype. Strains are mailed via bubble-lined mailing bags via First Class or Air Mail, with postage paid by the CGC except for commercial orders. The preparation of growth media involves the preparation of bacterial food sources, such as E. coli OP50, and the preparation of NGM petri plates. NGM plates are seeded with E. coli OP50 to provide a bacterial lawn for the worms. The preparation of NGM plates is detailed, including the use of a peristaltic pump and the addition of drugs if necessary. C. elegans is cultured on petri plates, with methods for transferring worms including chunking, filter paper transfer, and worm picking. The frequency of transferring worms depends on their genotype, temperature, and intended use. General stock maintenance tips include keeping worms between 16°C and 25°C, monitoring growth requirements, and ensuring proper labeling and storage of plates. C. elegans can also be grown in liquid medium, with protocols for preparing and maintaining liquid cultures. Contaminated stocks can be cleaned using various methods, including chunking, hypochlorite treatment, and egg prep. Synchronous cultures can be obtained by using axenized eggs and appropriate growth conditions. C. elegans stocks can be frozen and stored indefinitely in liquid nitrogen, with protocols for freezing using Liquid Freezing Solution or Soft Agar Freezing Solution. Recovery of frozen stocks involves thawing and transferring worms to NGM plates for reproduction and phenotyping. Freezing and recovery procedures are detailed, including the use of cryotubes and proper storage conditions. The chapter also includes acknowledgments and references to relevant literature.This chapter provides a comprehensive guide to the maintenance of C. elegans in the laboratory. It covers the acquisition of worm strains from the Caenorhabditis Genetics Center (CGC), methods of culture and transfer, decontamination of stocks, synchronizing and staging cultures, and procedures for freezing worms for long-term storage and for recovering them from the frozen state. The CGC provides C. elegans strains and information to researchers, and maintains an up-to-date bibliographic list of all articles, reviews, and books discussing C. elegans. The Worm Breeder's Gazette, a newsletter, is available for subscription. To acquire strains, researchers can submit a written request describing the strains, genes, or alleles desired and a brief statement of the intended use of the worms. The CGC provides strains for free to researchers at educational institutions or non-profit organizations, while commercial organizations must pay a fee. Strains are sent on NGM petri plates with the worms still feeding on E. coli OP50 or starved, depending on the strain's phenotype. Strains are mailed via bubble-lined mailing bags via First Class or Air Mail, with postage paid by the CGC except for commercial orders. The preparation of growth media involves the preparation of bacterial food sources, such as E. coli OP50, and the preparation of NGM petri plates. NGM plates are seeded with E. coli OP50 to provide a bacterial lawn for the worms. The preparation of NGM plates is detailed, including the use of a peristaltic pump and the addition of drugs if necessary. C. elegans is cultured on petri plates, with methods for transferring worms including chunking, filter paper transfer, and worm picking. The frequency of transferring worms depends on their genotype, temperature, and intended use. General stock maintenance tips include keeping worms between 16°C and 25°C, monitoring growth requirements, and ensuring proper labeling and storage of plates. C. elegans can also be grown in liquid medium, with protocols for preparing and maintaining liquid cultures. Contaminated stocks can be cleaned using various methods, including chunking, hypochlorite treatment, and egg prep. Synchronous cultures can be obtained by using axenized eggs and appropriate growth conditions. C. elegans stocks can be frozen and stored indefinitely in liquid nitrogen, with protocols for freezing using Liquid Freezing Solution or Soft Agar Freezing Solution. Recovery of frozen stocks involves thawing and transferring worms to NGM plates for reproduction and phenotyping. Freezing and recovery procedures are detailed, including the use of cryotubes and proper storage conditions. The chapter also includes acknowledgments and references to relevant literature.