This study focuses on assessing the contribution of ELL services to Spanish-speaking students' mathematics learning in elementary schools. ELL students tend to have lower average math achievement at school entry and throughout elementary school. The term "ELL services" encompasses English-as-a-second-language (ESL) programs, bilingual education programs, and other types of specialized programs for ELL students. Such students are entitled to support in the classroom until they achieve the level of English proficiency needed for full participation. Data were collected using outcome measures from math direct assessment scores. The assessment was administered in English if a student was proficient in English and was administered in Spanish if the student was proficient in Spanish but not in English. Study results indicate four or more years of ELL services on average are necessary to enable Spanish-speaking elementary students to become proficient in academic English essential for math learning. Yet a one-size-for-all recipe is practically naïve and often wasteful. Identifying the optimal length of ELL services for subpopulations of students therefore has immediate implications for ELL resource allocation. Tables and figures are appended.