This study investigates the various factors that influence investment decisionmaking, specifically focusing on five key variables: Family Influence, Innovation, Need for Achievement, Risk-Taking, and the relationship between Investment Decisions and Positive Word of Mouth. A quantitative research approach was employed, and data were analyzed using SPSS version 22.0. The study surveyed 250 respondents, consisting mostly of e-commerce users in Indonesia. The purpose was to examine how psychological and social variables impact individuals’ investment behaviors and how these behaviors contribute to subsequent outcomes such as word-of-mouth promotion. Five hypotheses were formulated and tested to determine the significance of each factor. The findings revealed that four out of the five hypotheses were supported. Family Influence, Innovation, and Need for Achievement were found to have a significant and positive effect on investment decision-making. In contrast, Risk-Taking showed no significant effect. Furthermore, Investment Decisions were shown to have a meaningful and positive relationship with Positive Word of Mouth, suggesting that confident and well-informed investment behavior can lead to increased consumer advocacy. The results underscore the importance for marketers and business strategists to understand and enhance the key drivers of investment behavior. By addressing these factors effectively, companies can encourage more favorable consumer decisions and foster stronger brand loyalty through word-of-mouth communication.