The　Internet　has　become　an　integral　part　of　our　daily　life,　and　how　to　make　the　best　use　of　the　Internet　is　important　to　both　individuals　and　the　society.　Based　on　previous　studies,　an　Online　and　Offline　Integration　Hypothesis　is　proposed　to　suggest　a　framework　for　considering　harmonious　and　balanced　Internet　use.　The　Integration　Hypothesis　proposes　that　healthier　patterns　of　Internet　usage　may　be　achieved　through　harmonious　integration　of　people＇s　online　and　offline　worlds.　An　online/offline　integration　is　proposed　to　unite　self-identity,　interpersonal　relationships,　and　social　functioning　with　both　cognitive　and　behavioral　aspects　by　following　the　principles　of　communication,　transfer,　consistency,　and　＂offline-first＂　priorities.　To　begin　to　test　the　hypothesis　regarding　the　relationship　between　integration　level　and　psychological　outcomes,　data　for　the　present　study　were　collected　from　626　undergraduate　students　(41.5%　males).　Participants　completed　scales　for　online　and　offline　integration,　Internet　addiction,　pros　and　cons　of　Internet　use,　loneliness,　extraversion,　and　life　satisfaction.　The　findings　revealed　that　subjects　with　higher　level　of　online/offline　integration　have　higher　life　satisfaction,　greater　extraversion,　and　more　positive　perceptions　of　the　Internet　and　less　loneliness,　lower　Internet　addiction,　and　fewer　negative　perceptions　of　the　Internet.　Integration　mediates　the　link　between　extraversion　and　psychological　outcomes,　and　it　may　be　the　mechanism　underlying　the　difference　between　the　＂rich　get　richer＂　and　social　compensation　hypotheses.　The　implications　of　the　online　and　offline　integration　hypothesis　are　discussed.