Child molestation (sexual assault or abuse) is generally defined as physical contact or other interaction between a child (under age 17, for example) and an adult when the child is being used for the sexual stimulation or pleasure of the perpetrator or another person. In addition to physical contact, child molestation may include (1) the exposure of the genitals of an adult in the presence of a child, (2) the exposure of the genitals of a child, (3) using a child in making pornography, or (4) making a child view sexual acts or pornography.

Child molestation laws vary from state to state, and criminal charges for child molestation and related crimes are sometimes called (1) sexual assault of a child, (2) aggravated sexual assault of a child, (3) sexual abuse of a child, (4) indecency with a child, (5) sexual performance by a child, (6) sexual trafficking of a child, or (7) prostitution of a child.

In some states multiple instances of sexual contact between an adult and a child may constitute the enhanced criminal offense of continual sexual abuse of a child—which is sometimes a first-degree felony offense.

Child molestation laws are usually included in a state’s penal or criminal code (statutes)—which provide for the related criminal charges—and in a state’s family code (statutes) that address the civil (non-criminal) implications of child molestation—often in the context of divorce and child custody matters.

Except in limited circumstances, federal laws generally do not apply to child sexual abuse matters that take place within a single state—without transportation of the child or other materials (photographs, videos, etc.) across state lines. Such criminal matters that take place within a single state are generally handled by state or local authorities and prosecuted under state laws. But if the sexual abuse or molestation of a child involves conduct or materials in multiple states, or occurs on federal lands (military bases, American Indian territories) the offense may be prosecuted under federal law.

In Massachusetts, child molestation, which encompasses a range of behaviors including physical contact for sexual gratification, exposure of genitals, involvement in pornography, and forcing a child to view sexual acts, is addressed under various statutes. The state defines a child as anyone under the age of 18. Crimes related to child molestation are prosecuted under the Massachusetts General Laws, particularly within Chapter 265, which covers crimes against chastity, morality, decency, and good order. Specific offenses include indecent assault and battery on a child under 14 (Section 13B), posing or exhibiting a child in a state of nudity (Section 29A), and procurement of sexual conduct for a fee (Section 53A), among others. Massachusetts law also recognizes the continuous sexual abuse of a child as a distinct and serious offense. In cases of child molestation, the state's family law may also come into play, particularly in matters of divorce and child custody. Federal laws may apply if the offense involves crossing state lines or federal jurisdictions, but otherwise, child molestation is typically prosecuted at the state level by local authorities.