The Commission issued a warning that Sweden, along with Austria and Germany, could face court action if they fail to act.
"In the absence of a satisfactory answer within two months, the Commission may decide to refer these countries to the Court of Justice of the European Union," the Commission warned in a statement on Wednesday.
The Commission pointed out that the EU's Free Movement Directive should have been adopted into national laws by April 2006 and that certain issues remained outstanding in some member states.
Infringement proceedings have previously been launched against a slew of EU countries, including Sweden, and a "third reasoned opinion" has now been sent to the country.
The Commission argued that it has identified 11 "issues of incomplete or incorrect transposition".
Key issues include the scope of Swedish law with regards to extended family members, which is deemed to be narrower than the directive.
Sweden is also accused of failing to "provide for a procedure to facilitate entry" or extended family members nor registration certificates, which are required by the directive.
Furthermore Sweden has no system to provide visas to family members free of charge, which the Commission argued "places a high administrative burden on family members".
The Commission called on Sweden to act within two months and warned that it would "closely monitor" all EU countries regarding their compliance with the directive.