This paper reports on a survey of past trends in national and sectoral R&D expenditure in New Zealand back to 1962 and models used to measure the rate of return to investment in R&D. Cobb Douglas models are compared with productivity models and are used to explore the interaction between R&D and labour and capital variables. Polynomial distributed lag models are investigated and the results compared with stock models. The average rates of return to R&D investment vary across sectors of the economy - some being surprisingly high - but some results remain ambiguous to interpret.