We present followup optical g ^ { \prime } , r ^ { \prime } , and i ^ { \prime } imaging and spectroscopy of serendipitous X-ray sources detected in 6 archival Chandra images included in the Chandra Multiwavelength Project ( ChaMP ) .
Of the 486 X-ray sources detected between 3 \times 10 ^ { -16 } 
and 2 \times 10 ^ { -13 } ( with a median flux of 3 \times 10 ^ { -15 } ) erg cm ^ { -2 }  s ^ { -1 } , we find optical counterparts for 377 ( 78 % ) , or 335 ( 68 % ) counting only unique counterparts .
We present spectroscopic classifications for 125 objects , representing 75 % of sources with { r ^ { \ast } } < 21 optical counterparts ( 63 % to { r ^ { \ast } } = 22 ) .
Of all classified objects , 63 ( 50 % ) are broad line AGN , which tend to be blue in ( g ^ { \ast } - r ^ { \ast } ) Â colors .
X-ray information efficiently segregates these quasars from stars , which otherwise strongly overlap in these SDSS colors until z > 3.5 .
We identify 28 sources ( 22 % ) as galaxies that show narrow emission lines , while 22 ( 18 % ) are absorption line galaxies .
Eight galaxies lacking broad line emission have X-ray luminosities that require they host an AGN ( log L _ { X } > 43 ) .
Half of these have hard X-ray emission suggesting that high gas columns obscure both the X-ray continuum and the broad emission line regions .
We find objects in our sample that show signs of X-ray or optical absorption , or both , but with no strong evidence that these properties are coupled .
ChaMP ’ s deep X-ray and optical imaging enable multiband selection of small and/or high-redshift groups and clusters .
In these 6 fields we have discovered 3 new clusters of galaxies , two with z > 0.4 , and one with photometric evidence for a similar redshift .