Social networking services (SNSs) have become very popular, and many Internet users use two or more SNSs. However, little research has been done to understand how and when users select multiple SNSs in series. This study investigates Internet users’ SNS selection behavior in daily life. We adopt the notion of media repertoire to explore how Internet users select SNSs in combination, and we adopt uses and gratifications theory to identify the values that drive these users to choose specific SNSs. We interviewed 40 Taiwanese people to explore the media traits, situational factors and social influences that affect users’ SNS selection behavior. The findings of this study can help SNS companies to improve SNS functions, and help marketers devise marketing strategies for target audiences and find suitable SNS platforms on which to communicate with consumers.