Through an extensive search of the published literature and collation of unpublished literature on programmatic experiences with developing and implementing integrated packages of SRH services, the Population Council gathered a body of evidence from which this guidance for UNFPA staff and national counterparts has been developed. Although the steps recommended for developing an essential SRH package are intended to provide a framework for developing any essential SRH package, UNFPA identified two priority areas to serve as examples for this guidance: 1) integrating family planning into maternal and newborn care services, and 2) integrating services for preventing and managing sexually transmitted infections (STIs)/reproductive tract infections (RTIs) into primary health care services. This guidance document comprises three sections. The Introduction explains and justifies why the development and implementation of an essential SRH package should be planned and framed within the World Health Organization's (WHO) six Building Blocks of Health Systems. The second section presents the "How To" steps and checklist tools for planning, implementing and scaling up an essential SRH package, including specific examples for the two priority areas indicated above. The third section provides the evidence-base supporting the recommendations and action-points proposed in each tool. This evidence-base includes key findings and summary recommendations from the literature review (in matrix format) and a bibliography of the references included in the literature review.