Set mostly in New York City, I Love Lucy centers on Lucy Ricardo, and her singer/bandleader husband Ricky Ricardo, along with their friends and landlords Fred Mertz and Ethel Mertz. During the 2nd season, Lucy and Ricky have a son named Little Ricky.
Lucy is somewhat naïve and ambitious, with an overactive imagination and a knack for getting herself into trouble. Primarily she is obsessed with joining her husband in show business. Fred and Ethel are former vaudevillians and this only strengthens her resolve to prove herself as a performer. The show provided Ball ample opportunity to display her considerable skill at clowning and physical comedy, with Lucy's determination to get into the act in any way possible, resulting in numerous wacky situations.
Lucy's husband, Ricky Ricardo, is an up-and-coming Cuban American singer and bandleader with an excitable personality. His patience is frequently tested, sometimes to the breaking point, by his wife's antics. When exasperated, he often reverts to speaking rapidly in Spanish. As with Lucy, not much was ever learned about his past or family.
Lucy's best friend, confidante and accomplice in her crazy schemes is Ethel Mertz. A former model from Albuquerque, New Mexico, Ethel tries to relive her glory days in vaudeville. She usually gets more chances to perform at Ricky's nightclub, because, unlike Lucy, she can actually sing and dance. Ethel, although she is Lucy's ally, often tries to reason with her, providing common sense advice.
Ethel's husband Fred served in World War I and lived through the Great Depression. He is very stingy with money and a very no-nonsense type of guy. However, he also shows that he can be a soft touch, especially when it comes to Little Ricky, the Ricardos' son. Fred performed in vaudeville, so like his wife Ethel, he can also sing and dance and they often performed duets.
Lucy and Ricky often play tricks on each other; for example, when Lucy tricked Ricky into thinking she was a compulsive thief; or when Ricky tricked Lucy into thinking she was not legally married to him, based on a mistake in their license. Although they may disagree at times, and despite their age differences (not only the Mertzes' and Ricardos', but Lucy and Desi's, with Lucy six years Desi's senior), the four main characters are very close and loving.