Isaac Cook Jr. was born in Kingston, Massachusetts. Isaac's father was a direct descendant of Mayflower passenger Francis Cooke, and his mother Rebecca Bradford was a direct descendant of Mayflower passenger and Plymouth governor William Bradford. The senior Cook died when Isaac was just one, but even without his father's guidance his child would go on to lead a long and adventurous life in the new republic of America.

Isaac first became a sea captain, then a farmer. In 1802 he married Jane Drew in a union that would produce two sons. Then, in around 1829 he became a brewer and established a stand at Cornhill square in Boston, Massachusetts. He later expanded and moved his brewery to 25 Central Street in that town. He prospered there until his death on March 20th of 1865 at the age of 83 years. Although both of Isaac's sons died before they could take over the brewery, the firm continued using the name Isaac Cook & Co. until 1895, a testament to the reputation its founder had cultivated over a lifetime of brewing.