Emojis are an extremely common occurrence in mobile communications, but their meaning is open to interpretation. We investigate motivations for their usage in mobile messaging in the US. This study asked 228 participants for the last time that they used one or more emojis in a conversational message, and collected that message, along with a description of the emojis’ intended meaning and function. We discuss functional distinctions between: adding additional emotional or situational meaning, adjusting tone, making a message more engaging to the recipient, conversation management, and relationship maintenance. We discuss lexical placement within messages, as well as social practices. We show that the social and linguistic function of emojis are complex and varied, and that supporting emojis can facilitate important conversational functions.