The current study attempts to explore and analyze errors of word choice made in written language by Saudi undergraduates at King Khalid University. It additionally tries to determine the probable sources of errors and provide remedies to them. The study focuses on word choice errors in four areas, viz., literal translation, collocation, subject /verb agreement, and word formation. Guided by a qualitative research design, the data was collected through a structured interview with two Writing teachers. Writing samples from final exams of 15 EFL learners were also collected. Analysis shows that literal translation is the highest frequency of error type (38.29 %), followed by collocation (28%), subject /verb agreement (21.14%), and parts of speech (12.57%). The study relates the errors to several factors including the impact of the Arabic language (L1), inappropriate teaching methods and learning strategies, inadequate mastery of appropriate English word usage, lack of collocation competence, limited students' vocabulary knowledge, and other factors. To assist students overcome and reduce word choice errors, the study presents some recommendations and pedagogical implications.