Zero has been philosophically and symbolically interpreted differently from other numbers throughout history. While it is foundational to all mathematics, in early grades, it is denounced as representing "nothing." In this study, the understanding of zero among students with learning disabilities (LD) and no learning disabilities (NLD) were investigated, and conceptual similarities and differences were examined. This research is a multiple-case study based on qualitative design. The study participants were six students, three with LD and three with NLD, aged between 10 and 12 years. Data were collected through clinical interviews that focused on zero as a number, the meaning of zero as "nothing," zero as the cardinality of an empty set, and zero's use as a symbol (place value, placeholder, digit). According to the findings obtained through the content analysis method, no patterns demonstrated clear distinctions between students with LD and NLD in interpreting zero as a number or the meanings of cardinality. In other words, LD and NLD students had differences and similarities in their zero understandings but were not sharp enough patterns to identify the groups. The students' explanations of their conceptualizations of zero provided some notable results. Significant misconceptions within all students' understandings of zero suggest the need for primary school mathematics teachers to pay more attention to the meaningful understanding of zero.