4-H in the United States is a youth organization administered by the National Institute of Food and Agriculture of the United States Department of Agriculture (USDA), with the mission of "engaging youth to reach their fullest potential while advancing the field of youth development." The name represents four personal development areas of focus for the organization: head, heart, hands, and health.

The organization has over 6.5 million members in the United States, from ages five to nineteen, in approximately 90,000 clubs. Clubs and related organizations now exist in many other countries as well; the organization and administration varies from country to country.

The goal of 4-H is to develop citizenship, leadership, and life skills of youth through mostly experiential learning programs. Though typically thought of as an agriculturally focused organization as a result of its history, 4-H today focuses on citizenship, healthy living, science, engineering, and technology programs.

Today, 4-H and related programs exist in over 80 countries around the world. Each of these programs operates independently, but cooperatively through international exchanges, global education programs, and communications.

The 4-H motto is "To make the best better", while its slogan is "Learn by doing" (sometimes written as "Learn to do by doing").

The foundations of 4-H began around the start of the twentieth century, with the work of several people in different parts of the United States. The focal point of 4-H has been the idea of practical and hands-on learning, which came from the desire to make public school education more connected to rural life. Early programs tied both public and private resources together to benefit rural youth.

During this time, researchers at experiment stations of the land-grant universities and USDA saw that adults in the farming community did not readily accept new agricultural discoveries, but educators found that youth would experiment with these new ideas and then share their experiences and successes with the adults. So rural youth programs became a way to introduce new agriculture technology to the adults.
 
A. B. Graham started one of the youth programs in Clark County, Ohio, in 1902, which is considered the birth of the 4-H program in the United States. The first club was called "The Tomato Club" or the "Corn Growing Club". T.A. "Dad" Erickson of Douglas County, Minnesota, started local agricultural after-school clubs and fairs also in 1902. Jessie Field Shambaugh developed the clover pin with an H on each leaf in 1910, and, by 1912, they were called 4-H clubs. The national 4-H organization was formed in 1914. When the United States Congress created the Cooperative Extension Service of the USDA by passage of the Smith-Lever Act of 1914, it included within the CES charter the work of various boys' and girls' clubs involved with agriculture, home economics and related subjects. By 1924, these clubs became organized as 4-H clubs, and the clover emblem was adopted.

The first 4-H camp was held in Randolph County, West Virginia. Originally, these camps were for what was referred to as "Corn Clubs". Campers slept in corn fields, in tents, only to wake up and work almost the entirety of each day. Superintendent of schools G. C. Adams began a boys' corn club in Newton County, Georgia, in 1904. However, the city of Jacksboro, Texas, also stakes a claim to having the first forerunner to 4-H in 1910.

4-H membership hit an all-time high in 1974 as a result of its popular educational program about nutrition, Mulligan Stew, shown in schools and on television across the country.

Pledge
The 4-H pledge is:
I pledge my head to clearer thinking,
my heart to greater loyalty,
my hands to larger service
and my health to better living,
for my club, my community, my country, and my world.

The original pledge was written by Otis E. Hall of Kansas in 1918. Some California 4-H clubs add either "As a true 4-H member" or "As a loyal 4-H member" at the beginning of the pledge. Minnesota and Maine 4-H clubs add "for my family" to the last line of the pledge. Originally, the pledge ended in "and my country". In 1973, "and my world" was added.

It is a common practice to involve hand motions to accompany these spoken words. While reciting the first line of the pledge, the speaker will point to their head with both of their hands. As the speaker recites the second line, they will place their right hand over their heart, much like during the Pledge of Allegiance. For the third line, the speaker will present their hands, palm side up, before them. For the fourth line, the speaker will motion to their body down their sides. And for the final line, the speaker will usually place their right hand out for club, left hand for community, bring them together for country, and then bring their hands upwards in a circle for world.

Emblem
The official 4-H emblem is a green four-leaf clover with a white H on each leaf standing for Head, Heart, Hands, and Health. White and green are the 4-H colors. The white symbolizes purity and the green represents growth.

The idea of using the four-leaf clover as an emblem for the 4-H program is credited to Oscar Herman Benson (1875–1951). When Wright County school superintendent Benson dropped by to visit a one-room schoolhouse near Clarion, Iowa, the students outside for recess presented him with a goodwill gift of seven just-picked four-leaf clovers. This simple gesture inspired Benson to select the four-leaf clover for the 4-H emblem. He awarded three-leaf and four-leaf clover pennants and pins for students' agricultural and domestic science exhibits at school fairs that Benson promoted.

The 4-H name and emblem have U.S. federal protection under federal code 18 U.S.C. 707. This federal protection makes it a mark unto and of itself with protection that supersedes the limited authorities of both a trademark and a copyright. The Secretary of Agriculture is given responsibility and stewardship for the 4-H name and emblem, at the direct request of the U.S. Congress. These protections place the 4-H emblem in a unique category of protected emblems, along with the U.S. Presidential Seal, Red Cross, Smokey Bear and the Olympic rings.