In general, heritage speakers experience linguistic insecurity about their heritage language. Linguistic insecurity, or the perception of one’s language variety as “inferior,” is shaped by language ideologies and can impact the development of cultural identity and language practices. However, it remains unclear how linguistic insecurity affects—or differs across—heritage speakers with varying levels of proficiency and language dominance. In this study, Spanish heritage speakers reported their experiences and emotions toward Spanish through questionnaires, think-aloud protocols (an introspective method), and focus groups. Information on language proficiency and dominance was collected through a questionnaire and an elicited imitation production task. An initial mixed-methods analysis was conducted. A cluster analysis based on proficiency and dominance scores yielded three groups: (1) Spanish-dominant with high proficiency, (2) English-dominant with high proficiency, and (3) English-dominant with low proficiency. Based on these three groupings, a qualitative analysis was carried out to understand how themes of linguistic insecurity, identity, and culture are manifested in groups with different linguistic profiles. Results suggest that all groups, regardless of proficiency and dominance, experience linguistic insecurity about their heritage language but the sources and the intensity of that insecurity differ across groups.