Social media platforms are deeply ingrained in society, and they offer many different spaces for people to engage with others. Unfortunately, accessibility barriers prevent people with disabilities from fully participating in these spaces. Social media users commonly post inaccessible media, including videos without captions (which are important for people who are deaf or hard of hearing) and images without alternative text (descriptions read aloud by screen readers for people who are blind). Users with motor impairments must find workarounds to deal with the complex user interfaces of these platforms, and users with cognitive disabilities may face barriers to composing and sharing information. Accessibility researchers, industry practitioners, and end-users with disabilities will come together to outline challenges and solutions for improving social media accessibility. The workshop starts with a panel of end-users with disabilities who will recount their Perspectives of Successes and Barriers. Industry professionals from social media companies (e.g., Facebook and LinkedIn) will detail their Design Process and Implementation Challenges in a panel with questions from attendees. The attendees will share their work and tackle Open Challenges and Future Research Directions. This workshop will forge collaborations between researchers and practitioners, and define high-priority accessibility challenges for social media platforms.