Abstract: The study examined the composite and relative influence of interpersonal and assertiveness skills on conflict-handling style of labour leaders in Lagos State, Nigeria. A descriptive survey research design of ex-post facto type was adopted for the study. Two hundred and fifty respondents (labour leaders) were purposively selected from ten randomly selected industrial unions in Lagos State. Data were collected through questionnaires and two hypotheses were tested at 0.05 alpha levels, using multiple regression. The findings revealed significant joint effect of interpersonal skill and assertiveness skill on conflict-handling style of labour leaders (F _(2,247) = 15.549, p<0.05), which implies that the two skills collectively are potent predictors of conflict-handling styles of labour leaders. Also, the result showed that assertiveness skill is a better predictor of labour leaders’ conflict-handling style with a significant relative effect of (B = 0.286, t = 5.242; p<0.05) while interpersonal skill had (B = 0.096, t = 2.167; p<0.05). Based on the findings, it was recommended among other things that training programme on the two skills be organized by governmenty for labour leaders on regular basis; learning materials on the acquisition of the two skills be incorporated into the induction training programme of organizations in the public and private sector; and that employers of labour in the organized private sector should replicate the training programme for top members of management who represent the management during negotiation with labour.