Table 4.

Summary of Hierarchical Regression Analyses Examining Main and Moderating Effects of Romantic Partner Characteristics on Adolescents’ Cigarette use, Alcohol Use, and Behavior Problems at Time 2

	Cigarette Use (8th grade)				Alcohol Use (8th grade)				Behavior Problems
	βstep	β	B	ΔR2	βstep	β	B	ΔR2	βstep	β	B	ΔR2
Step 1				.14*				.10				.10*
T1 Adolescent (Ad) Behavior	.38*	.18*	.25*		.32	.35	.36		.23*	.17	.27
Gradea									.16	.00	−.01
Step 2				.06				.05				.17***
T1 Best Friend Behavior	−.25	−.12	−.20		−.23	−.21	−.46		.42***	−.01	−.01
Step 3				.38***				.00				.03
T1 Romantic Partner (RP) Behavior	.63***	−.01	−.01		.08	.30	.87		.18	.00	−.03
Step 4				.18***				.00				.35***
T1 Ad x RP	.79***	.79***	3.11***		−.23	−.23	−1.21		.75***	−.11	−.27
T1 Ad x Gradea									.45***	.00	.01
T1 RP x Gradea									.72***	.00	−.06
Step 5												.29***
T1 Ad x RP x Gradea									.96***	.96***	7.69***
Total R2				.76***				.15				.94***

Note: At each step, ΔR² presented is for the step and β and B are for the final model,

^*p < .05.

^**p < .01.

^***p < .001.

^athe main and moderating effects of grade were only examined for behavior problems due to the lack of variability in cigarette and alcohol use among 6^th and 7^th graders.