By Matt Harrington, BCBA · Behaviorist Book Club · April 2026 · 12 min read

Stuck in Level 2: Identifying and Addressing Barriers to VB-MAPP Progress in Learners with Autism

Overview & Clinical Significance

The VB-MAPP and similar developmental language assessments have become the primary organizing frameworks for early intensive behavioral intervention with children with autism. These tools divide language and learning skills into developmental levels, with Level 2 (corresponding roughly to 18-30 month developmental equivalence) representing a pivotal stage: it is where children develop more sophisticated manding and tacting, begin engaging in listener responding at higher levels of complexity, and start building the social and play skills that enable peer interaction and learning in group settings.

For many children receiving ABA services, this level is also where progress plateaus. Patrick McGreevy's presentation examines the phenomenon of learners who receive appropriate early instruction, demonstrate initial progress, and then appear to stall within Level 2 for months or years without making the transitions expected by the assessment structure. This plateau is not a client failure — it is a clinical signal. It indicates that the instructional program has not adequately addressed the skill deficits or behavioral barriers that are preventing advancement.

Understanding why children get stuck in Level 2 requires a nuanced analysis of what Level 2 mastery actually demands. Advancing to pre-academic and academic curricula requires not just discrete verbal responses but the development of complex listener behavior, the capacity to respond to novel stimuli, motor imitation fluency, appropriate attending, and increasingly sophisticated social-communicative repertoires. When any of these prerequisite skills is absent or fragile, it can create a ceiling effect that prevents the broader advancement the assessment scores might otherwise suggest is imminent.

This course is valuable not because it provides simple solutions, but because it challenges BCBAs to look more carefully at why a learner who appears to be progressing is not actually moving forward — and to identify the specific instructional adjustments that are most likely to unlock advancement.

Background & Context

The VB-MAPP, developed by Mark Sundberg, is grounded in B.F. Skinner's verbal behavior framework and organizes language development according to verbal operants — mands, tacts, echoics, intraverbals, listener responding, and others — rather than the structural categories of traditional speech-language pathology. This operant framework has proven clinically useful because it directly maps to the teaching procedures that behavior analysts use and allows for fine-grained analysis of which specific verbal skills are present or absent.

Level 2 of the VB-MAPP spans a range of skills that, taken together, represent a significant developmental milestone: the transition from simple, discrete verbal responses to more flexible, generalized language use. This includes moving from simple tacting to feature-function-class tacting, from single-word manding to phrase-level manding under a range of motivating operations, and from simple motor imitation to verbal imitation in social contexts. Each of these transitions requires not just additional training on the surface form of the response but the development of underlying learning-to-learn behaviors.

Patrick McGreevy's work draws on extensive clinical observation of learners who present with strong discrete trial performance on specific VB-MAPP items but who fail to demonstrate the flexible, generalized language use that advancing to Level 3 and beyond requires. His analysis identifies a set of common skill deficits and instructional gaps that characterize the stuck-at-Level-2 profile, including overselective stimulus control, rote responding without conceptual generalization, insufficient manding to establish language as a functional behavior, and inadequate development of social learning skills.

This analysis connects to a broader issue in early intensive ABA: the difference between teaching to the assessment versus teaching to mastery. When instruction is organized primarily around achieving passing scores on VB-MAPP items rather than developing the robust, generalized repertoires those items are meant to sample, children may score at Level 2 but lack the actual behavioral flexibility that Level 2 performance is supposed to predict.

Clinical Implications

The stuck-at-Level-2 phenomenon has several specific clinical implications that should directly inform how BCBAs design and monitor early intervention programs. First, the issue of stimulus overselectivity deserves careful attention in program design. Stimulus overselectivity occurs when a learner responds to only a subset of relevant stimulus features rather than the full configuration of stimuli that defines a correct response. Children who appear to have mastered tacting but only respond correctly to highly familiar exemplars, or who mand successfully only with a specific therapist, are demonstrating overselectivity that will prevent generalization to novel stimuli and social contexts.

Addressing overselectivity requires deliberate programming for generalization from the earliest stages of skill acquisition. This includes using a minimum of three to five exemplars for every new concept, varying the instructional context (therapist, setting, materials) before mastery criterion is declared, and conducting frequent probe trials with novel exemplars to verify that generalization has occurred. BCBAs who wait until skills are mastered to address generalization will consistently produce learners who are stuck at their current level of development.

Second, the mand repertoire deserves particular scrutiny. The mand is the most functionally motivated verbal operant, and a robust manding repertoire is a prerequisite for the kind of language expansion that Level 3 and beyond requires. Children who have limited manding — who rely on problem behavior, gestures, or proximity to access reinforcers rather than verbal requests — lack the motivational foundation that drives language learning. Intensive mand training across a variety of motivating operations, using a wide range of items and activities the learner genuinely values, should be a priority for any child who appears stuck at Level 2.

Third, intraverbal development — the ability to respond to verbal stimuli with verbal responses in the absence of the original establishing operation — is often an underinvested area in early programs that contributes significantly to the Level 2 plateau. Intraverbal behavior underlies much of conversational language, reasoning, and social communication. BCBAs should audit their programs for the ratio of time spent on mand and tact instruction versus intraverbal training, and consider whether intraverbal deficits may be a primary contributor to their learners' plateaus.

Ethical Considerations

The ethical dimensions of the stuck-at-Level-2 problem center on the BCBA's obligation to provide effective treatment and to accurately represent treatment outcomes. Code 2.01 (Providing Effective Treatment) is directly implicated: a BCBA whose learner has been at Level 2 for an extended period without meaningful advancement has an obligation to critically analyze why progress has stalled and to modify the instructional program accordingly. Continuing the same program design while data show a persistent plateau is not consistent with this ethical obligation.

Code 2.15 (Interrupting or Discontinuing Services) and Code 2.19 (Documenting and Reporting Outcomes) together create a framework for how BCBAs should handle situations where expected treatment progress is not occurring. BCBAs should be transparent in their reporting to families and funding sources about the learner's current progress — including when that progress is slower than expected — and should document the clinical reasoning behind program modifications. Families who are receiving optimistic reports when their child's data tell a different story are not being served ethically.

Code 2.09 (Treatment Integrity) is also relevant. A program that is designed to address Level 2 deficits but that is implemented with low fidelity — where generalization probes are not conducted, where mand training is inconsistent, or where intraverbal instruction is skipped — may appear clinically sound on paper while being ineffective in practice. BCBAs are responsible for ensuring that the programs they design are implemented with sufficient fidelity to produce the expected outcomes, and for identifying fidelity failures when they occur.

Finally, Code 3.01 (Supervision Responsibilities) requires BCBAs to ensure that supervisees implementing programs for stuck-at-Level-2 learners understand the complexity of the clinical picture. The stuck-at-Level-2 profile requires instructional sophistication that goes beyond following discrete trial protocols. BCBAs supervising less experienced staff working with these learners must invest in developing their supervisees' clinical reasoning alongside their procedural skills.

Assessment & Decision-Making

Identifying why a specific learner is stuck at Level 2 requires a systematic reassessment that goes beyond re-administering the VB-MAPP. BCBAs should begin by analyzing the existing program data: how long has the learner been at this level? What specific items have been targeted repeatedly without mastery? Where are the inter-trial intervals, blocking, and reinforcement schedules in the current program, and are they appropriate for this learner's profile?

Next, a probing assessment should be conducted to examine generalization across exemplars, instructors, and settings for skills that are nominally mastered. A skill that scores as mastered on the VB-MAPP but fails to generalize to novel contexts is not actually mastered at the functional level. Identifying which mastered skills have genuine generalization and which are rote responses maintained only by very specific stimulus configurations is a critical first step in understanding the plateau.

The learner's mand profile warrants specific assessment. BCBAs should evaluate the range of motivating operations under which the learner mands, the topographies of manding used (vocal, picture exchange, AAC device), the spontaneity of manding versus prompted manding, and whether the learner uses mands to access a wide range of reinforcers or only a narrow set of highly preferred items. A restricted manding profile is a common contributor to the Level 2 plateau and a tractable instructional target.

Finally, an assessment of learning-to-learn behaviors — attending, turn-taking, imitation, conditional discrimination — should evaluate whether prerequisite skills for more complex instruction are present and robust. Children who have strong performance on discrete trial tasks but who struggle with group instruction formats, incidental teaching, or novel task formats may be lacking the learning-to-learn behaviors that academic settings will require. Identifying and systematically teaching these behaviors is often the key to unlocking advancement from Level 2.

What This Means for Your Practice

If you have a learner who has been working within VB-MAPP Level 2 for more than six months without meaningful advancement, McGreevy's framework suggests several immediate clinical actions. First, conduct a genuine reassessment of generalization — not just mastery of specific items but the flexibility and breadth of the learner's verbal repertoires. If tacting is strong with familiar items but collapses with novel exemplars, generalization programming has not been adequate. If manding is robust in therapy sessions but absent in the natural environment, motivating operations in the therapy context may not be ecologically valid.

Second, review your program's balance of verbal operants. Programs that are heavily weighted toward tact and listener responding at the expense of mand training and intraverbal development produce learners whose language profiles do not support the flexible, communicative repertoires that Level 3 advancement requires. Calculate the ratio of instructional time across verbal operants and consider whether rebalancing is needed.

Third, examine your generalization data systems. If your program does not include routine generalization probes with novel stimuli, you are flying blind. Mastery criteria that do not include generalization probes are clinically inadequate for any learner who has already shown a tendency to plateau. Build generalization probes into your data collection as a standard procedure, not an afterthought.

Finally, communicate clearly and honestly with families about the plateau and your plan to address it. Families who have been expecting steady progress may be confused or distressed when they learn their child has been at Level 2 for an extended period. Sharing your clinical analysis of the barriers, your revised instructional plan, and your data-collection approach builds trust and ensures that families are genuine partners in supporting their child's advancement.