Driven by a growth of single-person households and individualized lifestyles, solo dining in restaurants is an increasingly recognizable trend. However, little is known about solo diners’ motives and preferences in on- and off-premises restaurant dining and the subsequent behavioral intentions. In order to enhance the understanding of solo diners’ motives, preferences, and behavioral intentions in restaurant dining, this dissertation proposed and completed three studies related to solo (vs. group) diners’ menu-decision making process, solo (vs. group) diners’ service mode-decision making process, and a restaurant scale development for solo diner friendliness. Specifically, Study 1 examined the effect of dining social context (solo vs. group) on healthy or indulgent menu item decisions using self-control dilemmas and temporal construal theory as a theoretical framework. Findings revealed that solo diners showed less preferences for indulgent menu items because of a more utilitarian (i.e., less hedonic) consumption orientation than group diners, and that solo diners showed more preferences for healthy menu items than group diners when the menu included nutrition information such as calories, fat, and sodium. Study 2 examined the effect of dining social context (solo vs. group) on off-site over on-site dining intentions based on three mediators and the moderating role of self-determination using the self-determination theory. Findings revealed that, in the self-determined condition, solo diners showed more preferences for off-premises dining than group diners via greater convenience-seeking and polychronicity-seeking tendencies and lower anticipated enjoyment of on-premises dining. In the context-determined condition, solo diners showed more preferences for off-premises dining than group diners only via polychronicity-seeking and anticipated enjoyment of on-premises dining, and the effects were smaller. Lastly, Study 3 developed and validated a Solo Diner Friendliness (SoDF) scale that measured restaurant menu and service dimensions important for solo diners’ enjoyment as well as restaurant revisit intentions. The SoDF scale provided nine items under three factors, namely, <i>Inconspicuousness</i>, <i>Proper Service</i>, and <i>Healthy Menu Items</i>, that are valid and reliable measurements for future research and restaurant operators. Altogether, this dissertation offered theoretical and practical implications regarding how solo diners differed from group diners on various motivational and behavioral perspectives in on- and off-premises restaurant dining.<br>