Prior to the German invasion of Poland on September 1, 1939, Singer operated two thousand retail shops with a sales force of ten thousand in the United States. The Singer Sewing Centers sold sewing machines, vacuum cleaners, electric irons, electric Ribbonaire fans, stools, tables, and a variety of sewing machine accessories, attachments and parts as well as providing sewing instruction. The centers also conducted a sewing machine repair and rental business, and were equipped to mold the Singer dress form.

Sewing machine sales accounted for approximately two-thirds of the total volume of  Singer's domestic business. An average of six thousand machines were sold each week representing approximately 55% of the total household sewing machine sales in the United States.

Soon after the invasion of Poland, the production of household sewing machines was curtailed in favor of industrial sewing machines. In October of 1940, the US Selective Service Act went into effect. The male employees of Singer Sewing Centers joined the armed services and the female employees joined organizations such as the WACS and WAVES or left to work in war plants.

Regulation W, which prescribed minimum down payments, maximum maturities, and other terms applicable to extensions of consumer credit during World War II, was enacted on September 1, 1941. The ruling required a down payment of at least 20% on all sales and mandated that all payments must be completed within eighteen months. An even more stringent revision went into effect on March 1, 1942 increasing the down payment to 33 1/3%, while limiting the credit term to twelve months.

In March of 1942, three months after the attack on Pearl Harbor, Singer was advised that  manufacture of household sewing machines would be stopped in June of that year. By the end of 1942, Singer Sewing Centers were reduced from two thousand to six hundred and the sales force reduced from ten thousand to five thousand. Singer also immediately reduced the sales of sewing machines by 50%—from six thousand to three thousand a week—and developed a system of quotas to ration the current stock of machines. In compliance with the quota, in 1945 no more than five hundred sewing machines were sold in a single week in the entire United States. The production of attachments, electric irons, vacuum cleaners, and electric fans was also stopped.

The war created a revival of interest in home sewing which created a large demand for sewing machines. To address the need for machines, Singer stopped the sale of portable machines and used these machines to develop a nation-wide rental service. Singer also developed an advertising campaign to purchase little-used machines from consumers, reconditioned them, and sold them to consumers who would use them. Consumers willing to sell their machines to Singer were furnished with certificates of post-war priority which guaranteed preferential treatment when new machines became available. Additionally, Singer launched a campaign to repair existing machines. During the war, the service department reconditioned an average of 300,000 machines per year.

Singer also provided sewing classes and instructional material for sewers. To provide a quick brush-up for women who had sewn before, Singer developed courses in "Home Dressmaking", "Home Decorating" and "Alterations and Make-Over". Two sewing guides, the "Home Decoration Guide" and the "Dressmaking Guide" were updated and printed in large quantity and a new booklet, the "Singer Make-Over Guide", first published in 1942,  was created to help stretch the war-time wardrobe.

Sources: Singer in World War II - 1939 to 1945, Singer Manufacturing Company, USA, 1946; Franklin D. Roosevelt Archives & Digital Library; and the National Archives and Records Administration.