Dist. Ct. did not err in certifying for class action treatment under Rule 23(b)(2) claims of 4,000 participants in defendant’s pension plan where participants sought declaration that defendant violated ERISA by failing to give them credit for all pension benefits to which they were entitled. Dist. Ct. properly certified 10 different sub-classes based on participants' status as either early retiree or normal retiree, as well individual taking annuity or lump sum payment, and record showed that each sub-class satisfied homogenous requirement under Rule 23(b)(2), even though issues among sub-classes overlapped. Ct. further rejected defendant’s claim that proposed class action lacked commonality and further observed that instant class-action could be turned into Rule23(b)(3) class action requiring notice to members, as well as ability of members to opt out, should additional determination of monetary relief be required.