This study examined whether one Taiwan's heritage language immersion influences children's preference for the heritage language or cross-language. The research questions are: (1) What are children's attitudes toward the Hakka language (HL)? Does a significant difference exist in children's attitudes between those in the Hakka Language Immersion Program (HLIP) and children not participating in the program? (2) What are children's language preferences? Is there a significant difference in children's language preference between HLIP and non-HLIP (NHLIP)? This study used a causal comparative method to identify relationships between independent and dependent variables after the HLIP was implemented. The participants were selected from one HLIP (n = 37) and one NHLIP (n = 39). Both groups of children received a pretest and posttest, namely, the 'HL attitude measurement test,' which included 'HL opinion' and 'language preference' tests and had satisfactory reliability and validity. This study used covariate analysis to determine if a significant difference could be observed. The results demonstrated that the preference for the HL or cross-language in the HLIP was not significantly higher than those in the comparison group. Nevertheless, the children's HL preference in the cognitive domain and cross-language preference in the behavior domain exhibited a significantly positive effect.