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This study documented the etiology contributions between anxiety symptoms (AS) and depressive symptoms (DS) from ages 6–12 years. Teachers assessed AS and DS in 1112 twins at 5 time points. A genetic cross-lagged model was used to estimate genetic/environmental contributions to cross-sectional, cross-age and cross-lag associations. The variance in AS and DS was largely time-specific and more genetic in nature for DS than for AS. Previous DS predicted subsequent DS better than cross-lag or previous common effects, and AS up to age 9 better than previous AS or previous common effects. Thereafter, previous AS predicted subsequent AS. All predictions involved both genetic and unique environment. Suppression effects were found and, when controlled, AS marginally predicted DS from age 7 onward through genetic influences. AS and DS are associated throughout childhood. DS are more stable than AS, and more central to both subsequent AS and DS. AS marginally contribute to subsequent DS. [ABSTRACT FROM AUTHOR]