The National Institute of Standards and Technology (NIST) has developed a low-level peak power and pulse energy radiometer (APD 900) transfer standard for collimated laser light at a wavelength of 1064 nm. The peak power irradiance measurement range is from 500 pW/cm2 to 50 (mu) W/cm2 for laser pulse widths of 10 -250 ns. The pulse energy measurement range is from 0.05 fJ/cm2 to 50 pJ/cm2. The instrument combines the functions of peak power and pulse energy measurement into one unit, and improves the responsivity by two orders of magnitude greater than previous NIST designs calibrated at 1064 nm. The radiometer is based on an infrared-enhanced silicon avalanche photodiode with 100 mm diameter full aperture collecting optics. Selectable aperture sizes and a neutral density filter extend the measurement range of the instrument to higher levels, especially with large diameter beams. The output is a voltage waveform that can be measured with an oscilloscope. Calibration uncertainty for the APD 900 radiometer is typically less than +/- 8%. Improvements in the NIST calibration system will potentially lower the uncertainty to approximately +/- 5%.