Social Media, Leadership and Organisational Culture: The Case of Romanian Leaders -- Adolescent Sexting and its Associations With Parenting Styles and Sense of Parental Social Control -- Up for Debate: Effects of Formal Structure on Argumentation Quality in a Crowdsourcing Platform -- The Faceless Vicinity: Who Uses Location-Based Anonymous Social Networks Like Jodel and Why? -- Study on Influencing Factors on Internet Banking Usage during the SARS-CoV-2 Pandemic in Romania -- Empirical Modeling of e-Participation Services as Media Ecosystems -- Optimal Community-Generation Methods for Acquiring Extensive Knowledge on Twitter -- Being Part of an "Intermediate Community" and Aggressive Behavior on the Net: A Study on Cyberbullying Inside the Contrade of Siena in Italy -- Fake News Detection via English-to-Spanish Translation: Is it Really Useful? -- The Presumed Happiness of the Smiling Pile of Poo - How Emojis are Perceived by People -- Commenting or Discussing? Comment Sections of German Russian-Speaking News Media on Facebook -- Queermuseu - Frameworks in Social Network -- Human-Machine Interaction for Autonomous Vehicles: A Review -- Public Opinion Dynamics in Online Discussions: Cumulative Commenting and Micro-Level Spirals of Silence -- Global Agendas: Detection of Agenda Shifts in Cross-National Discussions using Neural-Network Text Summarization for Twitter -- Identifiability as an "Antidote": Exploring Emotional Contagion and the Role of Anonymity in Twitter Discussions on Misinformation -- Citizen Analytics: Statistical Tools for Studying Multicultural Environments and Distributed Cognition on Social Media -- Investigating the User Experience in the Process of Text Mining in Online Social Networks -- Analysis of User Relationships on Cooking Recipe Site Using Network Structure -- Multimodal Emotion Analysis based on Acoustic and Linguistic Features of the Voice -- Evaluation of Cooking Recipes Using Their Texts and Images -- Readability of Posts and User Engagement in Online Communities of Government Executive Bodies -- Effects of Conspiracy Thinking Style, Framing and Political Interest on Accuracy of Fake News Recognition by Social Media Users: Evidence from Russia, Kazakhstan and Ukraine -- Analysis of Modality-based Presentation Skills Using Sequential Models -- Testing Users' Ability to Recognize Fake News in Three Countries - An Experimental Perspective -- Public Responses and Concerns Regarding Vape Bans on Reddit: A Longitudinal Topic Modeling Approach -- ECUXH: A Set of User eXperience Heuristics for e-Commerce -- Ethical Design in e-Commerce: Case Studies -- Heuristics for Programming Codes -- Why Do We Love Coffee Even Though it is Bitter? -- Effective Management of Media Classes through Customer Journey Mapping -- Mixed Reality Interface for LoadApplication in Finite Element Analysis -- Identifying Customer eXperience Touchpoints in Tourism on the Hotel Industry -- Fairness in Design: A Tool for Guidance in Ethical Artificial Intelligence Desig -- Drone-based AI and 3D Reconstruction for Digital Twin Augmentation -- Estimating Interaction State from Nonverbal Cues and Utterance Events: A Preliminary Study to Support Ideation Facilitation in Living Lab -- A Preliminary Methodology to Evaluate the User Experience for People with Autism Spectrum Disorder -- One Profile, Many Memories: Projecting Memorials for Instagram Via Participatory Design.

This two-volume set LNCS 12774 and 12775 constitutes the refereed proceedings of the 13th International Conference on Social Computing and Social Media, SCSM 2021, held as part of the 23rd International Conference, HCI International 2021, which took place in July 2021. Due to COVID-19 pandemic the conference was held virtually. The total of 1276 papers and 241 posters included in the 39 HCII 2021 proceedings volumes was carefully reviewed and selected from 5222 submissions. The papers of SCSM 2021, Part I, are organized in topical sections named: Computer Mediated Communication; Social Network Analysis; Experience Design in Social Computing.