The shift of emphasis away from written to oral skills has stimulated an incipient concern in second language research to investigate ways of helping second and foreign language learners achieve higher degrees of oral proficiency. Priority solely taken over accuracy, complexity, or fluency of speech might be justifiable with regard to the context in which learning takes place. Accuracy and complexity have been suggested as paramount concern in syntactic processing typical of instructional contexts. The purpose of the present study was to investigate the effect of a training program on the grammatical complexity of 114 English Major Students at Islamic Azad University-Tabriz Branch at three different planning levels. A 2x3 factorial design was employed with two levels of metacognitive training, trained and untrained, and three levels of pre-task planning, on-line task planning, and pre/on-line task planning. It was hypothesized that the trained participants would produce more complex speech than the untrained ones, and that various planners would produce speech with varying degrees of complexity. Yet, the findings revealed no significant difference in terms of grammatical complexity among the trained and untrained participants. The findings suggest proficiency level and learners' attitudes and goals as main factors influencing the complexity of oral speech.