Holland is Director of the Latin American Socio-Religious Studies Program (known as PROLADES in Spanish, founded in 1977), with headquarters in San Jose, Costa Rica. He has lived in Costa Rica since 1972, and has worked with the Latin America Mission (Miami, FL) and IDEA Ministries (Santa Cruz, CA). He founded and served as the first director of the Missiological Institute of the Americas (1982), which has since become the Evangelical University of the Americas (UNELA, 1995), where he currently teaches Social Sciences and Religious Studies in Costa Rica and in UNELA extension programs in other countries.

While completing his M.A. program in Missiology at the School of World Mission, Fuller Theological Seminary (Pasadena, CA), in 1972, Holland conducted fieldwork on the Hispanic communities in Southern California and wrote The Religious Dimension in Hispanic Los Angeles: A Protestant Case Study (William Carey Library, 1974). He has since done fieldwork on religious groups in 20 countries of the Americas, as well as on Hispanics in the USA (1968-1971, 1980-1981 and 1992-1993) and on all ethnic and religious groups in the Los Angeles 5-county region of Southern California (1990-1995). He returned to Fuller Seminary in 1980-1981 for doctoral studies in Missiology and wrote "The History of the Protestant Movement in Central America, 1750-1980." He is the creator and developer of the Religion-in-the-Americas (RITA) Database Project (www.prolades.com), which includes information about all known religious groups in 50 countries. Since 1995, Holland has also been editor of the monthly news journal, MESOAMERICA, published in Costa Rica by the Institute for Central American Studies (ICAS).