Einstein A-coefficients for transitions among the 3s(2)3p3 states of S
II, calculated with the CIV3 code, are found to be up to approximately
25% different from those of Mendoza and Zeippen. These new results ar
e used to derive the theoretical emission line ratio R = I(3s(2)3p3 4S
3/2o-3s(2)3p3 2D5/2o)/ I(3S(2)3P3 4S3/2o-3s(2)3p3 2D3/2o) = I(6717 ang
strom)/I(6730 angstrom), which is a very useful electron density diagn
ostic for gaseous nebulae. The present diagnostics are up to approxima
tely 10% larger than those deduced using the A-values of Mendoza and Z
eippen, and will lead to electron density estimates up to approximatel
y 50% greater.