Beta- and gamma-ray spectroscopy, utilizing both single and coincident NaI(Tl) crystals and a magnetic spectrometer, has been used to study the radiations from Nb/sup 90/. The positron spectrum was resolved into components of 1.505 and 0.655 Mevs the internal-conversion electron spectrum was obtained, from which gamma-ray transitions of 0.132, 0.141, 0.372, 1.13, and 2.34 Mev were determined. The internal-conversion electron spectrum characteristic of the 1.76- Mev monopole transition en Zr/sup 90/ was also seen. The scintillation gamma-ray spectrum was resolved into components of level scheme for Zr/sup 90/ was formulated with excited states at 1.76(0+), 2.19(2+), 2.32(5--), 3.08(4+), 3.45(6+), tatively understood in terms of an independent-particle model. (auth)