Method for assembling a glass to a case to form a watch, the case having an annular surface which is intended to be bonded to a peripheral lower surface of an inner face of the glass; characterised in that the watch comprises a flange having an upper surface and sized to be able to be forcibly inserted, along an insertion axis, along an inner vertical surface of an upper part of the case, the inner vertical surface bounding the annular surface on the central side of the case; this assembly method comprising the following steps of: - partially inserting the flange into an opening defined by said inner vertical surface; - depositing an adhesive on the annular surface of the case and/or on said peripheral lower surface; followed by the following steps of: - bringing the glass against the upper surface of the flange in a final horizontal position of the glass in which the peripheral lower surface thereof is axially superimposed on the annular surface, the upper surface of the flange thus being in contact with a contact surface of the inner face of the glass adjacent to the peripheral lower surface, this contact surface and the upper surface of the flange being configured such that there is at least one continuous annular contact zone between these two surfaces; - exerting an axial pressure on an outer face of the glass with an intensity that allows the insertion of the flange into said opening to gradually continue until the upper surface of the flange has reached a final axial position, which position is provided above said annular surface, and until the peripheral lower surface of the glass is covered by the adhesive so as to form a continuous ring of adhesive between said annular surface of the case and the peripheral lower surface of the glass; - hardening the adhesive to form a tight joint. this assembly method comprising the following steps of: - partially inserting the flange into an opening defined by said inner vertical surface; - depositing an adhesive on the annular surface of the case and/or on said peripheral lower surface; - partially inserting the flange into an opening defined by said inner vertical surface; - depositing an adhesive on the annular surface of the case and/or on said peripheral lower surface; followed by the following steps of: - bringing the glass against the upper surface of the flange in a final horizontal position of the glass in which the peripheral lower surface thereof is axially superimposed on the annular surface, the upper surface of the flange thus being in contact with a contact surface of the inner face of the glass adjacent to the peripheral lower surface, this contact surface and the upper surface of the flange being configured such that there is at least one continuous annular contact zone between these two surfaces; - exerting an axial pressure on an outer face of the glass with an intensity that allows the insertion of the flange into said opening to gradually continue until the upper surface of the flange has reached a final axial position, which position is provided above said annular surface, and until the peripheral lower surface of the glass is covered by the adhesive so as to form a continuous ring of adhesive between said annular surface of the case and the peripheral lower surface of the glass; - hardening the adhesive to form a tight joint. - bringing the glass against the upper surface of the flange in a final horizontal position of the glass in which the peripheral lower surface thereof is axially superimposed on the annular surface, the upper surface of the flange thus being in contact with a contact surface of the inner face of the glass adjacent to the peripheral lower surface, this contact surface and the upper surface of the flange being configured such that there is at least one continuous annular contact zone between these two surfaces; - exerting an axial pressure on an outer face of the glass with an intensity that allows the insertion of the flange into said opening to gradually continue until the upper surface of the flange has reached a final axial position, which position is provided above said annular surface, and until the peripheral lower surface of the glass is covered by the adhesive so as to form a continuous ring of adhesive between said annular surface of the case and the peripheral lower surface of the glass; - hardening the adhesive to form a tight joint.