<p>Studies suggest that family motivation can increase employees’ performance because it integrates work and family roles. However, the literature overlooks the possibility that role integration between work and family may also trigger work-family conflict, which can decrease performance. To address this oversight, this study explores how and when family motivation influences employees’ in-role (i.e., task performance) and extra-role performance (i.e., helping behavior) through work-family conflict. Two field studies were conducted in China to test our hypotheses. Study 1 surveyed 362 employees and found that family motivation exerted an indirect adverse effect on both task performance and helping behavior through its impact on work-family conflict. Study 2 surveyed a sample of 481 employees and found that family motivation could stimulate work-family conflict via role integration, and that this mediated effect was stronger for employees with a high level of segmentation preference. This study advances the research on family motivation, and offers insights into ways to effectively manage work-family relationships.</p>