Abstract : Lexical sophistication provides a significant contribution to L2 writing quality which affects the power of the intended message. To explore the significance of the topic in public diplomacy, especially digital diplomacy, the current study aims to investigate the employment of lexical sophistication in digital diplomatic writings in one of the most common social media platforms used by diplomats, Twitter. The researcher investigates 24,000 tweets collected from 8 official foreign affairs accounts (3,000 tweets per account) over the period of 2019 to early 2023. Statistical analysis by means of the Tool for the Analysis of Lexical Sophistication (TAALES) was used, and it measures a wide range of classic and newly developed indices of lexical sophistication, including indices related to lexical properties at both the word and phrase level, and word and n-gram frequency, range, association strength, recognition norms, semantic network, contextual distinctiveness, and other indices, used to compare the production of L1 language users with L2 language users. To fulfill the aim of this study and answer the research questions, an L1 subcorpus was created, which included tweets from the FCDOGovUK account of the United Kingdom and the StateDept account of the United States of America. In addition to that, an L2 subcorpus was created and included tweets from various accounts representing different countries mainly the Kingdom of Bahrain, the Kingdom of Saudi Arabia, the United Arab Emirates, the State of Qatar, and the Republic of Tunisia. Findings of the analysis revealed that there is a difference in the total frequency of words. Native speakers’ tweets tend to be more expressive at the level of word frequency, while non-native speakers use more sophisticated lexical items. However, the numbers show a slight difference. Moreover, native speakers employ more formal styles with a slight difference as well. The most important implication is that Arab countries could pay more attention to their accounts in English. The study suggests that the construct of lexical sophistication is not restricted to the properties of words in isolation but involves collocational knowledge. Keywords: lexical sophistication, L1, L2, digital diplomacy, writing quality, Twitter