We analyze the cross-correlation of Mg II ( \lambda 2796 , 2803 ) quasar absorption systems with luminous red galaxies ( LRGs ) from the Fifth Data Release of the Sloan Digital Sky Survey . The absorption line sample consists of 2,705 unambiguously intervening Mg II absorption systems , detected at a 4 \sigma level , covering a redshift range ( 0.36 \leq z _ { abs } \leq 0.8 ) and a rest equivalent width range of 0.8Å \leq W _ { r } ^ { \lambda 2796 } \leq 5.0Å . We cross-correlate these absorbers with 1,495,604 LRGs with accurate photometric redshifts in the same redshift range and examine the relationship of Mg II equivalent width and clustering amplitude . We confirm with high precision a previously reported weak anti-correlation of equivalent width and the dark matter halo mass , measuring dark matter halo masses of Mg II absorbers to be log M _ { h } ( M _ { \sun } h ^ { -1 } ) = 11.29 \pm ^ { 0.36 } _ { 0.62 } for the W _ { r } \geq 1.4Å sample and log M _ { h } ( M _ { \sun } h ^ { -1 } ) = 12.70 \pm ^ { 0.53 } _ { 1.16 } for absorbers with 0.8Å \leq W _ { r } < 1.4Å . These measurements agree with previous reported values within the stated errors . Additionally , we investigate the significance of a number of potential sources of bias inherent in absorber-LRG cross-correlation measurements , including absorber velocity distributions and weak lensing of background quasars , which we determine is capable of producing a 20–30 % bias in angular cross-correlation measurements on scales less than 2 \arcmin . We measure the Mg II – LRG cross-correlation for 719 absorption systems with v < 60 , 000 km s ^ { -1 } in the quasar rest frame and find that these absorbers typically reside in dark matter haloes that are \sim 10–100 times more massive than those hosting unambiguously intervening Mg II absorbers . Furthermore , we find evidence for evolution of the redshift number density , \partial N / \partial z , with 2 \sigma significance for the strongest ( W _ { r } ^ { \lambda 2796 } \gtrsim 2.0 Å ) absorbers in the DR5 sample . This width-dependent \partial N / \partial z evolution does not significantly affect the recovered equivalent width–halo mass anti-correlation and adds to existing evidence that the strongest Mg II absorption systems are correlated with an evolving population of field galaxies at these redshifts , while the non-evolving \partial N / \partial z of the weakest absorbers more closely resembles the LRG population .