Effective corporate social responsibility (CSR) advertising depends on the nature of the partnership and how it is communicated in messages about CSR initiatives. Guided by the Symbolic Sustainability Model (SSM), this study investigates the effects of communication about CSR initiatives comparing differing CSR approaches through a 2 × 2 between-subjects factorial experiment. After viewing a hypothetical CSR-based advertisement, participants (N = 433) rated their perceptions of initiative effectiveness and attitudes toward the initiative. Compared to a donation-based initiative, a CSR partnership had an indirect, positive effect on audience evaluations, which was mediated by perceptions of the likelihood of the corporation’s sustained commitment to the partnership. The advertising that emphasized a partnership outperformed a donation-focused CSR initiative because participants perceived that the sponsoring corporation was invested in helping the cause for an extended period. The findings indicate that audiences are likely to perceive partnerships and donations positively; however, partnership initiatives may have stronger positive, indirect effects because they may be more likely to signal sustained commitment. The findings support the Symbiotic Sustainability Model (SSM) and demonstrate the efficacy of the SSM for CSR advertising. For practitioners, the findings point to strategies that may be helpful amidst the proliferation of CSR advertising.