For many years, thin‐window, single‐wire gas proportional counters were the only general‐purpose detectors available for nondispersive spectroscopy of low energy X‐rays. Their large area, low background, and coarse energy resolving capabilities, combined with their low cost, long lifetime, and ease of operation, mae them the workhorse instrument. During the last decade, solid state detectors and, more recently, gas scintillation proportional counters, have slowly replaced the standard gas proportional counter in many applications. Small are (0.2 cm2) Si(Li) detectors with 150 eV of FWHM noise have been used for fluorescence specctroscopy above 1 keV. However, their small area and cryogenic operation make these detectors less than ideal. Moreover, the nose in the associated electronics make these detectors useless below 0.4 keV. Gas sintillation proportional counters have now been developed to the point where they are the instrument of choice below 1 keV. Large are (≳100 cm2) counters with high sensitivity and low noise may be made relatively easily and inexpensively. Resolution sufficient to separate the nitrogen and oxygen K‐fluorescence lines have been achievd. Used with micron thin polypropylene windows, these counters have achieved 57% (FWHM) resolution at 149 eV sulfur L line. In addition, we have demonstrated that submillimeter imaging is possible with the gas scintillation proportional counter attached to a multiwire proportional counter. This paper will concentrate on a discussion of the principle of operation and design, and achieved levels of performance for the gas scintillation proportional counter. Where appropriate, their operation and performance will be compared to standard gas proportional counters and solid state detectors.