He was born to a Catalan father and a Puerto Rican mother of Galician descent. In 1934, he married Isabel García and had two children with her: Leon and Carolina. During Trujillo's dictatorship, Bosch was jailed for his political ideas, being released after several months. In 1938, Bosch managed to leave the country, settling in Puerto Rico.
By 1939 Bosch had gone to Cuba, where he directed an edition of the completed works of Eugenio María de Hostos, something that defined his patriotic and humanist ideals. In July, with other Dominican expatriates, he founded the Partido Revolucionario Dominicano (PRD), which stood out as the most active front against Trujillo outside the Dominican Republic.
Bosch heavily sympathised with leftist ideas, but he always denied any communist affiliation. He collaborated with the Cuban Revolutionary Party and had an important role in the making of the Constitution that was promulgated in 1940.
Bosch married for the second time, this time a Cuban lady, Carmen Quidiello, with whom he had two more children, Patricio and Barbara. At the same time, his literary career was ascending, gaining important acknowledgments like the Hernandez Catá Prize in Havana for short stories written by a Latin American author. His works had a deep social content, among them "La Noche Buena de Encarnación Mendoza", "Luis Pié", "The Masters" and "The Indian Manuel Sicuri", all of them described by critics as masterpieces of the sort.
Bosch was one of the main organizers of the abortive Cayo Confites expedition of 1947, in which a military force backed by the Caribbean Legion unsuccessfully attempted to invade the Dominican Republic from Cuba. Bosch fled to Venezuela after the expedition's failure, where he continued his anti-Trujillo campaign. In Cuba, where he returned by requirement of his friends in the Authentic Revolutionary Party, he played a notorious part in the political life of Havana, being recognized as a promoter of social legislation and author of the speech pronounced by President Carlos Prío Socarrás when the body of José Martí was transferred to Santiago de Cuba.
When Fulgencio Batista led a coup d'etat against Prío Socarrás and took over the presidency in 1952, Bosch was jailed by Batista's forces. After being liberated, he left Cuba and headed to Costa Rica, where he dedicated his time to pedagogical tasks, and to his activities as leader of the PRD.
In 1959 the Cuban Revolution took place, led by Fidel Castro, causing a major political, economic and social upheaval in the Caribbean island. Bosch accurately perceived the process that had begun from those events, and wrote a letter to Trujillo, dated February 27, 1961. He told Trujillo that his political role, in historical terms, had concluded in the Dominican Republic.
After 23 years in exile, Juan Bosch returned to his homeland months after Trujillo was assassinated on May 30, 1961. His presence in the national political life, as the Dominican Revolutionary Party presidential candidate, was a fresh change for the Dominicans. His manner of speaking, direct and simple, especially when addressing the lowest classes, appealed to farmers as much as people from the cities. Immediately he was accused by the Church and by conservatives of being a communist. However, in the elections of December 20, 1962, Bosch and his running mate, Armando González Tamayo, won a sweeping victory over Viriato Fiallo of the National Civic Union in what is acknowledged to be the first free election in the country's history.
On February 27, 1963, Bosch was sworn in as president in a ceremony that was attended by important democratic leaders and personalities, like Luis Muñoz and José Figueres. Bosch immediately launched a deep restructuring of the country. On April 29, he promulgated a new liberal constitution. The new document granted the people freedoms they had never known. Among other things, it declared specific labour rights, and mentioned unions, pregnant women, homeless people, the family, rights for the child and the young, for the farmers, and for illegitimate children.
However, Bosch faced powerful enemies. He moved to break up latifundia, drawing the ire of landowners. The Church thought Bosch was trying to oversecularize the country. Industrialists did not like the new Constitution's guarantees for the working class. The military, who previously enjoyed free rein, felt Bosch put them on too short a leash. In addition, the United States was skeptical of even a hint of left-leaning politics in the Caribbean after Fidel Castro openly declared himself a Communist.
On September 25, 1963, after only seven months in office, Bosch was overthrown in a coup led by Colonel Elías Wessin and replaced by a three-man military junta. Bosch went back to exile in Puerto Rico.
Less than two years later, growing dissatisfaction generated another military rebellion on April 24, 1965, that demanded Bosch's restoration. The insurgents, commanded by Colonel Francisco Caamaño, removed the junta from power on April 28. The United States dispatched 42,000 troops to the island during the ensuing civil war in support of the anti-Bosch forces.
An interim government was formed, and elections were fixed for July 1, 1966. Bosch returned to the country and ran as his party's presidential candidate. However, he ran a somewhat muted campaign, fearing for his safety and believing he'd be thrown out of office by the military again if he won. He was soundly defeated by Joaquín Balaguer, who garnered 57% of the vote.
During the last half of the 1960s, Bosch remained a very prolific writer of essays, both political and historical. He published some of his most important works during this time: "Dominican Social Composition", "Brief History of the Oligarchy in Santo Domingo", "From Christopher Columbus to Fidel Castro", and numerous articles of different sorts.
By 1970, Bosch had the intention of reorganizing the PRD, and turning its members into active, studious militants of the historical and social reality of the country. His project was not accepted by most of the PRD, most of whose members were turning in a more mainstream social democratic direction. Also, given the military repression, and lack of political equality between the PRD and the official Reformist Party, Bosch abstained from the 1970 elections.
The differences and contradictions between Bosch and an important sector of the PRD, as well as the corruption that had started to grow within the party, made him leave the organization in 1973, and thus he founded the Dominican Liberation Party (PLD) on December 15 of that same year.
Later he ran unsuccessfully for president as the PLD candidate in 1978, 1982, 1986, 1990, and 1994. He came closest to winning in 1990, but there were serious allegations of fraud against Balaguer.
After placing third in the 1994 election, Bosch retired from politics. He was already 83 years old and presumably suffering from Alzheimer's disease. In 1996 he was practically carried to the consolidation of the "Patriotic Front", an alliance between the PLD and his lifelong opponent Balaguer, as part of the latter's plan to defeat the PRD in the next presidential election.
Juan Bosch died on November 1, 2001, in Santo Domingo. As a former President, he received the corresponding honors at the National Palace, and was buried in his hometown of La Vega.
To this day, he is remembered as a man of principles. Over the years, as his luck rose and fell, his political direction oscillated wildly. He described himself as a "non-Communist" and a friend of Fidel Castro, and he told an interviewer in 1988 that he had never been Marxist.
In 2009, the writer Evelyn Marte published a book named Los Bosch Gaviño: apuntes y gráficas sobre su historia familiar which details the life of Juan Bosch and the Family.