This study comparatively analyses the syntax, semantics and pragmatic functions of conditional clauses in Tonga and English. It also establishes whether there are differences and similarities in the syntax, semantics and pragmatic functions of conditional clauses of both languages. The analysis done in this dissertation is on the (4) types of conditional sentences in the languages under study. The study analysed both secondary and primary data upon which it based its conclusions. In the analysis, the study has used the Speech Act Theory and the Cognitive Linguistic Approach. Analyses have shown that there are some similarities and differences in the syntax of conditionals in the two languages under study. However, similarities also do exist in the syntax, semantics and pragmatic functions of the conditionals. Just as English has several conditional markers including if, (which the study focused on). The study has shown that Tonga has several conditional markers (such as: kuti, naa, wa, noo, ni, ba, twa) equivalent to the English If. Other differences include the use of (in Tonga conditionals as opposed to English counterparts) a whole sentence represented either by subject and verb or by a verb plus an enclitic. It is evident from the findings that conditional clauses account largely for tools mostly used in conversation in both Tonga and English, in oral and written discourse, though the written discourse is not discussed here. When used in conversation, initialised if-clauses can be used to give directives, speak humorously and sarcastically and offer apologies, commands, advice and instructions (Celce-Murcia & Larsen Freeman, 1999). The study has also shown that, as opposed to Tonga speakers, English speakers, in certain instances prefer to introduce strong arguments (e.g. I will visit you soon if I buy a car) and indeed interesting topics in the main clause, which necessitate final position for the subordinate conditional clause as well as those that are long and involved. The analysis has in addition shown factors that determine the position of the if-clause. Such factors as Topic continuity, parallelism and qualification apart from the principle of end-focus have been seen as determining the position of the if-clause. Under the semantic analysis, it has been learnt that in the Tonga Zero conditional, there is the prominence of when than the kuti (if). As for the second conditional, the expression in the main clause refers much to the present than the future. Interpretations of conditionals in this paper are based on a number of form meaning correlations such as their verb forms and compatibility between the protasis and the apodosis. The analysis of conditionals in this study is in line with (Maye’s 1994), and has shown, that conditionals help us explore the relationship between language and the human mind. In this case, conditionals are seen as reflecting the psychological thoughts and the state of speaker (sorrow, regret). These aspects are shown in the use of predictive and future temporal conditionals by both Tonga and English speakers. The study on the whole has contrasted conditional clauses in Tonga and English at syntactic, semantic and pragmatic levels. The study recommends further studies on conducting a comparative analysis of the Tonga conditionals and other Zambian or Bantu languages.