The Parroquia Nuestra Señora del Carmen was founded in 1893 in the coastal town of Cataño, Puerto Rico. In 1957, the Dominican Catholic Order commissioned architect Henry Klumb to design a modern church, which was inaugurated in June 1962. Since its opening, the Del Carmen Church has remained relatively unchanged, yet efforts to maintain and 'improve' the building over the years, including painting the original exposed cement stucco exteriors, an important character-defining feature of its design; has contributed toward a misunderstanding and underappreciation of one of Klumb's most significant works on the island. This case study examines Henry Klumb's original design intent for the Del Carmen Church and its subsequent alterations over time, including the current conditions of the concrete and exterior cement stucco in the tropical coastal environment of Puerto Rico. The study was comprised of four phases: Firstly, an in-depth analysis of archival research of the building, its design, the historical context, and its construction and maintenance. The second phases include a conditions survey and assessment with a detailed focus and evaluation of the exterior Portland cement stucco. The third phase focused on physico-chemical analysis of selected samples from the cement stucco and the concrete substrates that included: petrography, micro-drop water absorption testing, microchemical spot test, salt content, carbonation testing, x-ray diffraction (XRD), and scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDS). The last phase recommends a cleaning program to determine the best treatment options for removing the current painted coatings without affecting the cement stucco and aiding the building's restoration to its original appareance. Henry Klumb's Del Carmen Church in Cataño, Puerto Rico, exemplifies how common conservation issues for modern heritage, such as design intent, weathering, authenticity, and material realities, are global concerns and how informed scientific investigations can aid in better interpretation and conservation.