Previous research has documented positive effects of pre-task planning on task-based performance, commonly analyzed in terms of complexity, accuracy, and fluency, in an L2. However, the sources of planning have rarely been examined in the research of task-based language teaching. The present study explored EFL learners' oral performance across the three sources of pre-task planning--teacher-led, group-based, and solitary--and their perceptions toward pre-task planning. Forty-eight L1 Korean college students were divided into four different source-of-planning conditions and took a decision-making task in English. Results show that there was a general planning effect on the learners' fluency and complexity. The solitary planning condition was effective in producing more fluent speech, and the group-based planning condition produced the highest syntactic complexity scores. The teacher-led planning condition helped learners produce L2 speech that is more accurate and richer in vocabulary, but the effects on accuracy were not statistically significant. Most of the planners perceived the opportunity for planning to be beneficial, but some behavioral differences were found among the planning groups, providing some implications for the implementation of pre-task planning.