Different from the traditional term language input, affordance, an ecological term, has been deployed to analyze the perceived opportunities for second language (L2) learning an environment provides to L2 learners. L2 learning occurs only when the semiotic resources in the environment resonate with the learner's capacities such as their abilities, aptitudes, and attitudes. Adopting affordance as a theoretical and analytic construct, this study investigates using qualitative research methods what language development affordances WeChat, one of the most popular Social Networking Systems in Chinese-speaking communities, provided to two university-level Chinese language learners while they were studying abroad in an intensive language program in Shanghai. Four affordances were identified. The results also show that each affordance was manifested differently with each language learner due to unique communication norms on WeChat, each language learner's Chinese language proficiency, and their personal preference in WeChat communication. Pedagogical implications are also provided to guide educators and L2 users as to how to take advantage of WeChat for language learning.