With a large , unique spectroscopic survey in the fields of 28 galaxy-scale strong gravitational lenses , we identify groups of galaxies in the 26 adequately-sampled fields . Using a group finding algorithm , we find 210 groups with at least five member galaxies ; the median number of members is eight . Our sample spans redshifts of 0.04 \leq z _ { grp } \leq 0.76 with a median of 0.31 , including 174 groups with 0.1 < z _ { grp } < 0.6 . Groups have radial velocity dispersions of 60 \leq \sigma _ { grp } \leq 1200 km s ^ { -1 } with a median of 350 km s ^ { -1 } . We also discover a supergroup in field B0712+472 at z = 0.29 consisting of three main groups . We recover groups similar to \sim 85 % of those previously reported in these fields within our redshift range of sensitivity and find 187 new groups with at least five members . The properties of our group catalog , specifically 1 ) the distribution of \sigma _ { grp } , 2 ) the fraction of all sample galaxies that are group members , and 3 ) the fraction of groups with significant substructure , are consistent with those for other catalogs . The distribution of group virial masses agrees well with theoretical expectations . Of the lens galaxies , 12 of 26 ( 46 % ) ( B1422+231 , B1600+434 , B2114+022 , FBQS J0951+2635 , HE0435-1223 , HST J14113+5211 , MG0751+2716 , MGJ1654+1346 , PG 1115+080 , Q ER 0047-2808 , RXJ1131-1231 , and WFI J2033-4723 ) are members of groups with at least five galaxies , and one more ( B0712+472 ) belongs to an additional , visually identified group candidate . There are groups not associated with the lens that still are likely to affect the lens model ; in six of 25 ( 24 % ) fields ( excluding the supergroup ) , there is at least one massive ( \sigma _ { grp } \geq 500 km s ^ { -1 } ) group or group candidate projected within 2 ^ { \prime } of the lens .