He received the APA International Humanitarian Award from American Psychological Association[1] Prewitt Díaz was born in Cayey, Puerto Rico.

[6] He served as Squadron Commander, Red Cross Liaison, and Legislative Affairs Officer for the Pennsylvania Wing and achieved the rank of lieutenant colonel.

The World Education Fellowship 1975–1978 allowed him to study language development and cultural adjustment of Puerto Rican children in Connecticut.

A Woodrow Wilson Hispanic Fellowship resulted in the first draft of a 1994 book entitled The Psychology of Puerto Rican Migration, an ethnographic study.

Once the student achieves in the 30th percentile of the Language Assessment Battery, they are placed in the mainstream classrooms with support[15] Good things were happening in Bilingual Education.

[21][22][23] His work in exploring the linguistically applicability of Standardized test, the mechanics of developing and translating test has been used in the fields of educational psychology and psychosocial support internationally[24][25][26] His weekly long trips from State College, PA to Bethlehem, Chester, Lancaster, and York provided a laboratory for graduate students, an opportunity for parents to seek advice on how to improve the academic and psychosocial well being of their children.

He served in the mid-1990s as a Pastor of the “El Mesías” United Methodist Church in Philadelphia, where he experienced first hand the emotional and spiritual challenges of non-English speaking people living in a large urban environment.

Dr. Joseph O Prewitt Diaz served as volunteer for the American Red Cross since 1976, when he organized Blood drives at Bulkeley High School, Hartford, Connecticut.

Prewitt Díaz helped to train Red Cross volunteers in mental health support in the wake of the January 2001 and February 2001 earthquakes.

[37][38] When the 2004 tsunami battered the shores of South Asian countries, the American Red Cross psychosocial support team based in India and led by disaster mental health expert, Joseph Prewitt Díaz, quickly responded to the devastated to Sri Lanka, the Maldives, and Indonesia to assist in developing programs.

[39] Prewitt Díaz made significant adaptations to the psychosocial support program on the basis of his extensive experience in Hurricane Mitch in Central America, the earthquake-affected area in Bhuj and the riot-torn camps in Gujarat.

In the critical early weeks following the tsunami, American Red Cross-trained volunteers in psychological first aid developed programs in Maldives, Sri Lanka, Indonesia and India.

[39] These psychosocial programs initiated by the American Red Cross team planned to provide service to the children and their families in communities and schools.

The impact was the large number of ordinary people, especially women, got involved in a project that brought hope, taught them new skills, and increased their feeling of self-efficacy.

Prewitt Díaz has been recognized for his outstanding achievements and contributions to the education and well-being marginalized children and youth by two Pennsylvania governors.

The following are selected books over a twenty-year period: He was the primary author (with Dr. Robert Trotter III and Victor Rivera) of a three-year study titled "The effects of migration on children.