The use of English as L2 for communication is the main purpose behind the teaching and learning of English and the whole task of ESL teaching and learning revolves around its use for communicative purpose. This study is an effort to explore the reasons because of which some of the students seek L2 use more frequently while others avoid it. The present study is carried out to estimate the effect of motivation, willingness to communicate (WTC), self-perceived communicative competence (SPCC) and L2 anxiety (ANX) on the frequency of use of English as L2 for oral communication (FREQ). Moreover, the study aims to explore which of the motivation, WTC, SPCC and ANX has comparatively more or less effect on FREQ. 123 University students studying English at post graduate level (MA English) participated in the study. A survey questionnaire was used as a data collection tool for the study. SPSS20.0 software was applied to find out the values of mean, standard deviation, correlation coefficient and co-efficient of regression among the variables. The results showed that within the four variables; motivation, WTC, SPCC and L2 anxiety; SPCC is found to be the first, WTC is the 2nd and motivation is the 3rd positively influencing variable that affect FREQ among post graduate students of English in Pakistan. Anxiety is found to have a weak and negative effect on FREQ.