Ben (who rode a horse named Buck) ran the Ponderosa with help of his loyal Asian cook, Hop Sing (Victor Sen Yung) and his three grown sons (each born of different mothers). Ben's sons included:

• Pernell Roberts as Adam Cartwright, the oldest
• Dan Blocker as Eric "Hoss" Cartwright, the middle son.
• Michael Landon as  Joseph "Little Joe" Cartwright, the youngest

Adam Cartwright, the university educated son, was the poet of the family. He enjoyed reading literature and sampling the finer things in life. But, Adam was also an accomplished horsemen and could hold his own in a gun fight. He rode a horse named Beauty (and Sport).

Adam, considered the most serious of the sons, was the only one to leave the Ponderosa. Like his father, who had been a ship's first mate in his younger days, Adam set to sea as a sailor. From time to time, he sent letters home to keep his family up-to-date about his travels abroad. Adam never returned home.

Adam's mother was Elizabeth Stoddard (Geraldine Brooks), the daughter of ship's Captain with whom Ben worked as a first mate. Elizabeth died from complications from giving birth to Adam. Consequently, his father Ben, decided to leave New England and his job at a chandler store (goods or equipment dealer) and travel west to California. But they settled in St. Joseph, Missouri where Ben fell in love with his second wife.

Hoss Cartwright is the easy-going middle son. He is a big man with equally big appetite. He was always at odds with Hop Sing, the ranch cook and often chased away while attempting to raid the kitchen for something to eat. Hoss always heeded Hop Sing's warnings, however, because he didn't want to get on the bad side of the man that provided such wonderful meals. Hoss rode a horse named Chub (and Ginger and Piute).

One of the funniest things to happen to Hoss was the time he thought he saw leprechauns in the woods near the Ponderosa. When he reported the tale of little green men to his family, they burst out laughing.

The little green men turned out to be a band of dwarf circus performers who were trying to retrieve a box of gold that contained their life's savings which Hoss found in the woods.

Initially, the discovery of that cache of gold coins caused an influx of frantic fortune hunters who trespassed on the Ponderosa with shovels in hand with the hope of finding their own pot of gold.

Hoss' mother was a Swedish girl named Inger Borgstrom (Inga Swenson) whom Ben had fallen in love with while he lived in St. Joseph, Missouri. She was killed during an Indian attack while traveling to California with Ben and Adam.

Before she died, Inger gave birth to Hoss (whom she called Eric). Eric used his middle name Hoss, which is a Swedish mountain term for a big, friendly man. After Inger died, Ben gave up his dream of traveling to California and settled in Virginia City, Nevada where he established his Ponderosa empire in the wilderness on the outskirts of  town.

Joseph "Little Joe" Cartwright was the youngest son. He was the lover boy of the bunch, always courting the prettiest girl in the area. Joe was also the most emotional, as well, often losing his temper at the drop of a hat, and usually when it involved a woman.

Mischievous at heart, Joe was always thinking up schemes to make a fast buck. He often recruited his gullible brother, Hoss (who should know better - per Ben) to help with his endeavors which usually had unforeseen consequences. Joe rode a pinto hose named Cochise (and Paint).

Joe's mother was a Marie De Marne (Felica Fatt), a French woman whom Ben Cartwright met during a trip to New Orleans. She was the widow of ranch hand who had saved Ben's life. Ben traveled to Louisiana to fulfill the man's last request. Romance ensues and Marie returns to Virginian City as Ben's wife. She gives birth to Little Joe but then tragically falls from her horse and dies.

Map of the Ponderosa ranch

Other persons of note in the lives of the Cartwrights included:

• Ray Teal as Sheriff Roy Coffee, the law in Virginia City
• David Canary as "Candy" Canaday, the ranch foreman.
• Guy Madison as Will Cartwright, a Ben's handsome nephew. who visited the Ponderosa for a short time.
• Bruce Yarnell as Muley Jones, Ben's cousin
• Lou Frizzel as Dusty Rhoades, Ben's friend.
• Mitch Vogel as Jamie Hunter-Cartwright, a red-haired teenager whom Ben adopted as a son. Dusty had taken charge of Jamie after his rainmaker dad died.
• Tim Matheson as Griff King, Candy's friend and ex-convict who took a job at the Ponderosa.

Listen to Theme Music

Theme Song Lyrics
(Lyrics never used on the show)

We got a right to pick a little fight - Bonanza!
If anyone fights anyone of us he’s gotta fight with me!

We’re not a one to saddle up and run: Bonanza!
Anyone of us who starts a little fuss knows he can count on me.

One for four. Four for one: This we guarantee.

We got a right to pick a little fight: Bonanza!
If anyone fights anyone of us he’s gotta fight with me!