| 1900 | |
| 1903 | Milton Hershey builds a chocolate factory and a town for his workers near Harrisburg, Pennsylvania. |
| 1904 | |
| 1906 | The town of Derry Church, Pennsylvania changes its name to Hershey to honor Milton S. Hershey. |
| 1907 | |
| 1908 | |
| 1908 | `The Hershey Chocolate Company makes the first milk chocolate bar with almonds. |
| 1909 | The Hershey Chocolate Company states making Silvertops. This is a version of the Hershey's Kisses that are sold individually. They are discontinued in 1931. |
| 1911 | Frank and Ethel Mars build a candy company in Tacoma, Washington. Later it become the Mars, Inc. |
| 1912 | Jean Neuhaus, Jr. invents the first chocolate covered praline. He fills the empty chocolate shell with pralines invented by his father. |
| 1912 | The Whitman Company produces the boxed assortments called Whitman's Samplers. This is the first company to have a drawing of where the different chocolates are located in the box. |
| 1914 | |
| 1919 | The Fry family merges with the Cadbury Brothers. |
| 1921 | The Hershey Food Corporation begins to wrap the Kisses by machine and add the flag to the wrapping. |
| 1921 | |
| 1922 | |
| 1923 | |
| 1923 | Hershey Foods Corporation registers the name Hershey's Kisses as a trademark. |
| 1925 | |
| 1927 | Baker's Chocolate Company is bought by General Foods Corporation. They move the company to Delaware. |
| 1927 | The Hershey Chocolate Company is renamed Hershey Chocolate Corporation. |
| 1928 | L. S. Heath & Sons, Inc. develops the toffee candy bar called the Heath Bar. This candy bar can be bought on the home-delivered dairy order form. |
| 1929 | Frank Mars opens the Chicago candy plant. |
| 1929 | Peter, Cailler, and Kohler merge with Nestlé ending 30 years of rivalry between the two companies. |
| 1930 | |
| 1938 | The Hershey Chocolate Corporation makes the Krackel bar. |
| 1939 | Blommer Chocolate Company begins manufacturing in Chicago, Illinois. It will become the largest commercial chocolate manufacturer in the United States. |
| 1939 | Hershey makes the Hershey's Miniatures chocolate bars. |
| 1941 | Forrest Mars returns to the United States from England. He goes into business with Bruce Murrie, who is the one of the president of the Hershey Chocolate Company. They call their new company M & M Ltd. Together they make the first M & M's. |
| 1947 | |
| 1950 | Sam Altshuler starts the Annabelle Candy Company, Inc. He names his company for his daughter and makes the first Rocky Road candy bar. |
| 1962 | Hershey's Kisses are wrapped in colors other than silver for the first time. |
| 1963 | Hershey Chocolate Company buy H. B. Reese Candy Company, Inc. for $23.5 million. |
| 1966 | The Campbell Soup Company buys the Godiva Chocolatier, Inc. of Belgium. |
| 1969 | The Cadbury chocolate business merges with the Schweppes soft drinks to form Cadbury Schweppes. |
| 1970 | The Tobler company merges with the Suchard to become the largest chocolate company. |
| 1970 | Because the Reese's Peanut Butter Cups are so popular the company has to double its size. |
| 1973 | The Cadbury Company opens Chocolate World theme park in Bournville, England. |
| 1973 | The Hershey Foods Corporation opens its theme park, Hershey's Chocolate World. |
| 1973 | Hershey Foods begins putting nutritional information on their labels. |
| 1976 | Hershey Chocolate Company adds chopped peanuts to the Reese's Peanut Butter Cups to make Reese's Crunchy. |
| 1977 | Hershey Foods makes the first Golden Almond chocolate bar. |
| 1980 | An employee of the Schare-Tobler tries to sell secret chocolate recipes to Saudi Arabia, China, and Russia. Luckily he was unsuccessful. |
| 1988 | Nestlé buys the British chocolate and candy manufactures Rowntree. This makes Nestlé the world's largest chocolate manufacturer. |
| 1988 | Hershey Chocolate Company is renamed Hershey Chocolate U.S.A. The company buys Peter Paul. |
| 1989 | |
| 1990 | Hershey sends 144,000 of their heat-resistant candy bars to soldiers in the Gulf War, Desert Storm. |
| 1991 | The recipe for Reese's Peanut Butter Cup is changed to add three times the amount of peanuts. |
| 1993 | The first Hershey's Hugs and mini Hershey's Kisses wrapped in white chocolate are sold. |