Attendance at sporting events remains a vital part of sporting contests, as spectators have been shown to have a significant impact upon the atmosphere of an event (Uhrich & Benkenstein, 2012). As more attractive options for consuming sporting events continue to arise (e.g., higher-definition televisions, game watch parties, etc.), sport managers should seek to better understand what elements of in-person spectating are most important for repeat attendance. Sport stadium atmosphere researchers have identified other spectators as a positive source of influence for future attendance intentions (Biscaia, Correia Rosado, Maroco, & Ross, 2012; Lee, Lee, Seo, & Green, 2012; Uhrich & Benkenstein, 2012). However, spectators have only been studied in aggregate, as though all spectators were homogenous and part of one entire group. Through the present research I evaluated a specific sub-group, the Official Supporter’s Group (OSG) Section, of the spectating population for its effects on the non-OSG spectators in attendance at Major League Soccer games. The stated purpose of the OSG Section is to assist their team through chants, singing, and cheering. As a means of achieving this goal, those within the OSG Section attempt to involve other spectators outside the section to increase the volume and intensity of support for their team. The existence of these supporter’s groups is explained through Social Identity Theory and Complexity Theory. OSGs and the OSG Section are theorized to be sub-components of the Sport Stadium Atmosphere (SSA) framework (Uhrich & Benkenstein, 2010; Uhrich & Koenigstorfer, 2009). This framework consists of three dimensions of environmental stimuli (organizer-induced, game-induced, and spectator-induced) that have a positive, direct relationship with consumer affective responses (Uhrich & Benkenstein, 2010). This research was conducted to evaluate the impact of those making up the OSG Section as an influential aspect of the spectator-induced dimension. The two goals of this research were to add to the SSA framework (Uhrich & Benkenstein, 2010; Uhrich & Koenigstorfer, 2009) in two ways: 1) by evaluating the effect of a previously unstudied aspect of the spectating population: the OSG Section, and 2) by including satisfaction as a measure of the effects of the stadium atmosphere upon the consumer. Three stages were employed to investigate the goals above. First, a questionnaire was developed to survey spectators of Major League Soccer (MLS) games during the 2018 season. Item-development processes were undertaken, based on the recommendations of Hinkin’s (1998) scale development process, to evaluate perceived effects of the organizer-induced stimuli, game-induced stimuli, the influence of the OSG Section, and outcome variables of satisfaction, intention to return, and word-of-mouth recommendations. Second, a pilot study was conducted to evaluate the new items developed and to refine the instrument for the main study. Finally, a main study was employed to collect data from a second sample of the population (MLS spectators) using the refined survey instrument. Confirmatory factor analysis and structural equation modeling techniques were used to analyze collected data and test the hypothesized relationships. The members and actions of those comprising the OSG Section were found to have a significant, positive relationship with both resulting spectator emotions and satisfaction. Further, there is evidence to further confirm the relationship between satisfaction and behavioral intentions (Kuenzel & Yassim, 2007; Matsuoka et al., 2003). Practical implications, limitations, and future research directions are all discussed in the final chapter.