The current paper investigates speech rhythm in the L2 variety of English spoken in the Kingdom of Tonga, an island nation in the South Pacific, using the quantitative metrics nPVI-V, rPVI-C and %V. In addition to classifying Tongan English in relation other varieties of English, external constraints on variation in speech rhythm are examined. A corpus of conversational and read speech recorded with 48 Tongan English speakers is used in analysis. Results indicate that inter-speaker variation exists, with education, occupation and index of English use are significant constraints on variation. The vocalic metrics, nPVI-V and %V, had greater explanatory power, proving to be more robust measures of variation than rPVI-C.