Several commercial companies to foster immigration from Britain were founded in the 1820s and 1830s, but their attempts to establish settlements in New Zealand failed until the New Zealand Company landed its first immigrants at Port Nicholson (Wellington) in January 1840. Within two years, further settlements were established under the company's auspices at Nelson and Wanganui, while further north the Plymouth Company of New Zealand – formed mainly of Devonshire people – purchased land from the New Zealand Company and began the settlement of New Plymouth. In the years 1840 to 1850 the New Zealand Company made a vital contribution to the early settlement of the country by bringing out some 12,000 settlers. It also inspired the founding of two other settlement associations, the Otago Association which commenced a Scottish settlement at Dunedin in 1848, and the Canterbury Association which sponsored an English settlement in Christchurch in 1850. In the meantime, the Government of the colony was active in encouraging immigrants to settle in Auckland which had been chosen by Governor Hobson as the seat of administration.

It has been estimated that by 1841 the European population was 5,000, doubling again within 12 months, and rising to 22,000 in 1850. The first census of the European population in 1851 gave the population as 26,707, and in the next seven years to the second census the population rose steeply to 59,413, the rate of increase averaging 12.7 per cent a year. This high rate of population expansion was exceeded in the next two intercensal periods, being 18.3 per cent a year between 1858 and 1861 and reaching the phenomenal rate of 20.7 per cent a year between 1861 and 1864. As a result, the European population rose to 97,904 in December 1861 and 171,009 in December 1864. The large part that immigration played in these increases can be clearly seen in diagram 1.