Prior research offers little guidance on how competence-based brand factors can help transmitting positive word of mouth (PWOM). Building upon signaling theory, we propose that a brand’s efforts into innovativeness reinforce the message that “we have the competence to deliver what promised,” which in turn generates PWOM. We collected longitudinal survey data using two measurement waves with a 4 week interval among respondents from an online customer panel. The results indicate that brand innovativeness has an indirect positive relationship with PWOM, mediated by perceived brand expertise. We also find that altruism positively moderates the relationship between perceived brand expertise and PWOM. The theoretical contributions and managerial implications are also discussed.