Construction and a-Efficiency of Nested Partially Balanced Bipartite Block Designs R package NPBBBdesigns version 1.0.0 Construction and evaluation of nested partially balanced bipartite block (NPBBB) designs for comparing a set of test treatments with a set of control treatments under a nested (blocks within blocks) structure. Six systematic construction methods are provided: composing partially balanced bipartite block designs with nested balanced incomplete block designs; augmenting nested partially balanced incomplete block designs with controls; merging rows of group-divisible nested designs; direct construction from group-divisible schemes; and expansion of partially balanced incomplete block designs (Vinayaka et al. 2026: In press). The A-efficiencies of the block and sub-block classifications are computed against the A-optimal completely symmetric reference design, following the test-versus-control optimality framework of Gupta and Parsad (1996) <doi:10.1080/03610929608831743> and Vinayaka et al. (2024) <doi:10.1080/03610926.2023.2251623>. These designs are particularly suited to agricultural, animal husbandry, industrial, and clinical trials involving multiple standard checks under nested experimental conditions, such as multi-environment trials where field heterogeneity (blocks) and within-field variation (sub-blocks) must be controlled simultaneously. Software Depends: R (>= 3.5.0) Vinayaka <vinayaka.b3vs@gmail.com> Comprehensive R Archive Network (CRAN) Vinayaka [aut, cre] (ORCID: <https://orcid.org/0000-0001-5004-0084>), Rajender Parsad [aut, ctb], B.N. Mandal [aut, ctb], L.N. Vinaykumar [aut, ctb], Gopalareddy Krishnappa [aut, ctb] (ORCID: <https://orcid.org/0000-0002-8825-6363>) GPL-3 2026-07-04 application/tgz https://CRAN.R-project.org/package=NPBBBdesigns doi:10.32614/CRAN.package.NPBBBdesigns