The　emergence　and　evolution　of　cooperation　in　complex　natural,　social　and　economical　systems　is　an　interdisciplinary　topic　of　recent　interest.　This　paper　focuses　on　the　cooperation　on　complex　networks　using　the　approach　of　evolutionary　games.　In　particular,　the　phenomenon　of　diversity-optimized　cooperation　is　briefly　reviewed　and　the　effect　of　network　clustering　on　cooperation　is　treated　in　detail.　For　the　latter,　a　general　type　of　public　goods　games　is　used　with　the　result　that,　for　fixed　average　degree　and　degree　distributions　in　the　underlying　network,　a　high　clustering　coefficient　can　promote　cooperation.　Basic　quantities　such　as　the　cooperator　and　defector　clusters,　mean　payoffs　of　cooperators　and　defectors　along　their　respective　boundaries,　the　fraction　of　cooperators　for　different　classes　as　well　as　the　mean　payoffs　of　hubs　in　scale-free　networks　are　also　investigated.　Since　strong　clustering　is　typical　in　many　social　networks,　these　results　provide　insights　into　the　emergence　of　cooperation　in　such　networks.　©　2012　World　Scientific　Publishing　Company.