This study examines the impact of writing instruction on Spanish heritage language (SHL) learners' attitudes towards digital stories (DS) and self-efficacy beliefs with regard to academic writing, multiliteracies, and computer abilities. Two types of writing instruction--a traditional curriculum centered around genres and a multiliteracies curriculum consisting of the interpretation and design of DSs--were implemented in fourth and fifth-semester SHL courses at a US university in the Southwest. Drawing on Gardner's (1985) conceptualization of attitude, and Bandura's (1991) construct of perceived self-efficacy, a survey was designed to explore changes in participants' (n = 225) scores before and after the treatments. Confirmatory factor analysis was conducted to determine the reliability of the instrument and a latent mean structure analysis was used to explore differences among groups before and after the 16-week intervention period. Findings indicate that curricular changes aimed at developing multiliteracies benefitted participants in two of the four domains under examination: attitude towards DSs and self-efficacy in multiliteracies abilities. Areas in which participants exposed to the multiliteracies curriculum did not experience a positive impact--self-efficacy in academic writing abilities and computer abilities--provide insights into how multiliteracies abilities develop and potential modifications that can be implemented in the curriculum to maximize its positive impact.